"The soul of every living creature blesses Your Name, Almighty God, and the spirit of all flesh glorifies and exalts Your mention, O King… We are inadequate to thank You… and to bless Your name for even one of the millions of favors You have shown our forefathers and us… and so, the limbs You have granted us and the breath and the soul with which You have inspired us and the tongue You have placed in our mouths - they will thank You and bless You and praise You… for every mouth shall thank You, and every tongue shall swear allegiance to You, and every knee shall bend before You, and every man of stature shall prostrate himself before You, and every heart shall hold You in awe, and all our inner parts shall sing praises to Your Name" _{(From the prayer Nishmat Kol Hai)}

In his book, Hovoth Ha-Levavoth (The Obligations of the Hearts; section Avodath Ha-Elokim "Worshipping God"), Rabbeinu Bahye ben Pakuda explained at length that a person is obliged to worship God in two ways:

1. on the basis of his intelligence, in accordance with his natural understanding; and,
2. because of the Commandments of the Torah.

He went on to explain that man's obligation to his Creator stems mainly from the fact that he is obliged to show the Creator gratitude for all His favors. Ingratitude towards the Creator is an extremely serious matter, and for that reason an ingrate loses his spiritual world. It says in the Talmud (Bava Kama 16a-b): "A man's spine becomes a snake after seven years - if he has not bent his knee upon reaching the Modim prayer in the 'Amidah". One of the commentators adduced by Tosafot writes: "The Midrash explains that there is a strong, inflexible bone in one's spine from which one is formed in the future… and now that that bone has become a snake, the man will not live in the future". Tosafot itself does not agree with this and says: "It is not reasonable to say that one will incur so severe a punishment for this misdeed, for 'the entire Jewish people has a portion in the World to Come", and so that commentator must mean the following: That the act of bending the knee at Modim is an expression of self-negation before the Almighty, for all His favors, as we say in that prayer… "for Your miracles and Your wonders at all times, evening, morning and midday". One who does not acknowledge this is an ingrate, and this is indeed a very serious matter. We find something similar in the serious sins committed by Jehoiakim, as brought down (in Sanhedrin 113b), where a list appears of all the serious sins committed by those people who have no portion in the World to Come:

Menasseh erased the Name of the Almighty from the Torah and tore down the Altar.
Amon burnt the Torah and offered up a lizard [an impure offering] on the altar.
Ahaz permitted promiscuity.
Menasseh fornicated with his sister.
Amon fornicated with his mother.

His mother asked him: "Do you find enjoyment in the place from which you came into the world?" He replied: "I am only doing this to anger my Creator". Yet there is an even more serious transgression: "When Jehoiakim came he said: My predecessors did not know how to anger [the Creator with all their terrible deeds, though they committed the most serious of sins, doing so not because of their evil inclination, but merely in order to infuriate the Almighty; what then is still to be done? And then he said:] Do we need anything but His light? We have pure gold which we use - let Him take His light! People said to him: But the gold and silver are His - as we find "For Mine is the silver and Mine is the gold, says the Lord of Hosts!" He replied: "He has already given it to us," as is written: "The heavens are the heavens of the Lord, and the earth He has given to the sons of men". From this we see just how serious ingratitude is, for all the deeds committed by all those evil people in order to anger the Almighty do not equal the wickedness of ingratitude and diminish the value of His goodness - to compare the sun, which is our source of heat, and the energy which creates food by photosynthesis, and an infinite number of other favors the Almighty grants us by means of them, to pure gold is extremely serious, since man must recognize the goodness of the Creator. For this reason the characteristic of gratitude was formulated, and for this reason a person cannot talk back to those to whom he is in debt. Rashi explains it as (Bava Kama 109): "because He did good for him". In addition, we see how powerful bribery is - it joins with the one who gives the bribery, and this is true with the smallest of matter, like extending one's hand to assist the judge in disembarking from the boat to the shore, or removing the feather from the judge's head or covering up the spit that lay before him on the path, even though these were all acts the judge did not ask for. Nevertheless, our Sages disqualified themselves for judging in such cases, as noted above (Ketubbot 105b).

Now, since this is the case, one feels gratitude even to an inanimate object, as in the case of the Ten Plagues. Moshe did not strike the Nile or the dust of Egypt because he gained something from them; they themselves had no intention of assisting Moshe, and were not aware of Moshe's feeling of gratitude towards them - yet this sense of gratitude is imprinted on the human soul. This is the way one is to behave.

Our Sages said as follows:

(Bava Kama 92a): "A pit from which you have drunk water - you may not throw a stone at it!" One of our Talmudic commentators, the Shitta Mekubbetzet, wrote in this connection that the meaning of this rule is that you should neither scorn such a pit nor repay it with evil doing, after you have benefited from it. This serves as a analogy for other matters: One who has benefited in some way from a certain person should never do any deed which may lead to that person being harmed. The Sages remarked in the Talmud on this matter; they adduced parables and verses concerning the Plagues in Egypt, and revealed the reason some of them were performed by Moshe's brother Aaron. One Sage related that he had this problem with a certain person, and so refused to judge him at all, so as not to judge him in a way that might bring harm to him - thus he refused outright. Then there was the case of the man who fell ill, and visited a person who had a bath in his home [until not that long ago, most homes in Jerusalem did not even have a shower stall. People would bathe at the mikveh or in a tub in the kitchen, and so the aforementioned bath was an extremely costly matter], and benefited from that bath. Afterwards, he invited him to stay with him until he recovered, and honored him and favored him - and he recovered. In the meantime, the wealthy man lost his property in various ways. He undertook to repay debtors but could not, until he had no choice but to sell the aforementioned bath and to pay his debtors with it. R. Yitzhak said: I will not in any way rule concerning that bath - not in a sale, not in an evaluation, not in any way concerning it - because I benefited from it. If he ruled this way regarding an inanimate object, how much more would he hate to rule regarding human beings who can sense harm and usefulness, so that anyone doing so could be considered immoral."

Since gratitude is very obligatory, there are people who reject favors or who are reluctant to accept them so as not to have to show gratitude for them. The sages have said (Avoda Zara 5a): "The rabbis learned with regard to the verse, 'Who can ensure that their hearts always be…'; Moshe said to the Israelite people: My children are ungrateful, ungrateful, for when the Almighty said of Israel 'Who can ensure that their hearts always be…', you should have said: 'You can ensure it'!" The Tosafot explained that he called them ingrates, children of ingrates because they did not want to say "You can ensure it" - because they did not want to have to show gratitude for that. Similarly, it is written, "And we are sick at the spoiled (k'lokel) bread". Rashi explained that the manna was light, and because it was readily absorbed directly into their limbs and they had no need to defecate - and so they called it "spoiled" and showed their displeasure with it. Whereas in fact it was a great favor - that they had no need to go outside the camp so long a distance to defecate". Children of ingrates - this refers to Adam who said "the woman You have given me - she gave me the fruit of the tree and I ate it". This showed ingratitude, for he attributed his own misdeed to the gift he had received from the Almighty, that he had made his helper".

One who shows gratitude to human beings and to all creatures is grateful to the Almighty as well. Our Sages have said: "One who shows no gratitude to his friend will in the end be ungrateful to the Almighty". In this way, one becomes a servant of the Almighty.