The Mesilas Yesharim (ch.20) discusses the thoughts one should have when he wants to do a good deed, but he isn't sure whether it is Hashem's will. He recommends that he should think through all angles of the issue. "He should turn to all sides of the matter that he can see, until he can judge whether he should do it or refrain.... Because there are times that the deed seems good, but since the outcome of this deed is bad, he shouldn't do it..."
We quote some more from the Mesilas Yesharim: "We now have to discuss משקל החסידות, weighing chassidus. This is a very important subject and a primary aspect of becoming a chasid. This is truly the hardest part of chassidus because it is a very thin line, and the yetzer hara has a large opening here. He is in great danger because there are many good deeds that the yetzer hara can push away, claiming that they are bad, and there are many aveiros that the yetzer hara will say are terrific mitzvos. The only way to succeed in weighing these matters is with the following three contemplations:
- His heart must be straight. His sole intention should be to make a nachas ruach for Hashem without any other considerations.
- He should study his deeds and seek to improve them for this purpose [of doing Hashem's will. He should think about the outcome of this deed and determine whether ultimately good will come from it or the opposite.]
- And after all the above, he should place his trust in Hashem.... But if one of these details is lacking...it is more likely that he will make a mistake and fall."
