Avos chapter 3, mishnah 13 (and in some versions 3:10). Rabbi Chanina ben Dosa used to say: "Kol she'ruach ha'briyos nochah heimenu - ruach ha'Makom nochah heimenu; v'chol she'ein ruach ha'briyos nochah heimenu - ein ruach ha'Makom nochah heimenu".
The wording is difficult to translate literally, and this is what it means:
"Kol she'ruach ha'briyos nochah heimenu" - anyone whom people enjoy and derive pleasure from, and who leaves them satisfied with his conduct - the Holy One, Blessed is He, is likewise satisfied with him and derives pleasure from him.
"V'chol she'ein ruach ha'briyos nochah heimenu" - anyone from whom people derive no pleasure and with whose conduct they are not satisfied - the Holy One, Blessed is He, likewise derives no pleasure, delight or enjoyment from him.
A sign, not a cause:
This is a very simple message, yet it is easy to misunderstand at first glance. It does not mean that a person should make it his goal to please people, and that this is what the Holy One, Blessed is He, asks of him. That is not the point. People's approval and their satisfaction with his conduct are not the reason for the deed; they are the sign - the result of the fact that he is doing the right thing. A person's focus should be solely on giving pleasure to the Holy One, Blessed is He, on the will of Hashem and on what the Holy One, Blessed is He, asks of him, and that is all that should occupy him.
However, focusing on doing the right thing before the Holy One, Blessed is He, does not necessarily mean that it is being done in the way that the Holy One, Blessed is He, wants it done. The test, the barometer, the sign and the indication by which a person knows that he is acting properly and in the right way is that people are pleased with him, that they are satisfied with him and approve of what he does. If he irritates those around him, nobody likes what he does and nobody wants to be near him, people are frustrated by him and complain about him - then even if he believes that he is acting purely for the sake of Heaven and doing everything correctly, and even if, Heaven forbid, he is not actually doing anything wrong, he is not doing it in the right way, and therefore the Holy One, Blessed is He, is not pleased.
Conversely, if a person focuses on doing the right thing and everyone is pleased with him because he is a great tzaddik - that is a good sign. It is no simple matter for people to be pleased with a person's conduct, and it means that he acts with sensitivity, in an 'oisgehalten' way, with judgment, with humanity and with consideration. This is part of the matter itself: it is not enough that nothing bad be done. A person must refrain from doing anything bad, and in addition must act in a way that leaves people comfortable with his conduct, without feeling discomfort, frustration or anger. Therefore, when a person does not earn the goodwill of those around him, that is a good sign that he is conducting his service of Hashem in a way that irritates people, and consequently he is doing it in a way that also irritates the Holy One, Blessed is He. This is the plain meaning of the mishnah as most students understand it, and it is very important - it sounds simple, but it is not simple at all.
Rabbeinu Yonah's approach - in dealings and in business:
There is a completely different approach, that of Rabbeinu Yonah, according to which the mishnah is not speaking about service of Hashem in general, but about business matters specifically. The idea is that when a person is a businessman whom everyone finds frustrating, and those who come to deal with him do so only out of necessity, viewing him as a swindler or as overly demanding or inconsiderate - then he is going about it in the wrong way. The way a person is to conduct his business affairs is a way in which he is permitted to earn a living; he is not required to be a doormat, but neither must he always win, never compromise and demand more than is reasonable.
If the people he works with - whether his suppliers, his employees or his customers - derive no pleasure from him, meaning that they do not want to be his suppliers, his employees or his partners because he is too hard and too severe, that is a sign that he is doing something improper. It is possible that he is doing something even worse than that: cheating, lying, stealing, acting dishonestly, unreasonably or oppressively. But even if not, the point here is that in business a person must conduct his trade in a way that people are happy to deal with him, and that he be a person of integrity and pleasantness.
If people are pleased with his dealings and derive satisfaction from him, that is a good sign that he is doing it properly; and if they are not pleased, that is a good sign that he is doing something improper, in Heaven's eyes as well. From the perspective of the Holy One, Blessed is He, a person is doing something improper when the people he works with are not pleased with the way he runs his business.
In summary: in this mishnah we learned that people's satisfaction is not the goal but the sign - an indication and a test that a person is doing the right thing in the right way. According to the plain meaning it refers to service of Hashem as a whole, and according to Rabbeinu Yonah it refers to the conduct of one's dealings and business; and in both approaches the principle is one: it is not enough to refrain from evil, rather a way of sensitivity, consideration and integrity is required, in which people are pleased - and consequently the Holy One, Blessed is He, is pleased with him as well.