1,235. Illness
191:6 It is prohibited for a Jew to have a non-Jew castrate an animal for him. Some authorities even prohibit a Jew to sell an animal to a non-Jew, or even to give it to him in exchange for half the profits, if he knows that the non-Jew will castrate it. This is because non-Jews also have an obligation not to castrate animals, so the Jew would be violating lifnei iver, the prohibition against causing others to stumble. However, if the non-Jewish buyer doesn't castrate the animal himself, but he gives it to another non-Jew to castrate, then all authorities agree that the Jew is permitted to sell it to him because such indirect consequences are permitted.
192:1 Rav Yitzchak the son of Rav Yehuda said that a person should always ask for mercy so that he shouldn't get sick, because if he get does sick, Heaven asks him to demonstrate some merit to release himself from it. Mar Ukva says that we can infer this concept from Deuteronomy 22:8, "the faller will fall from it." The Hebrew word "mimenu" ("from it") can also mean "from him," i.e., once one has fallen, it is up to him to provide proof that he deserves to be relieved.
The Talmud also says that if a person has a headache, he should consider himself as if in chains. If he becomes bedridden, he should view it like being brought to the court where capital crimes are heard. When a person is judged, if he has powerful advocates, he will be saved. If not, he won't be saved. And what are a person's advocates? Repentance and good deeds. Even if 999 testify against him, if one testifies in his favor, he will be saved, as per Job 33:23-24, "If he has one angel advocating for him out of a thousand to declare him upright, then He will be gracious to him and say, 'Spare him from going down to the grave...." (All this from Talmud Shabbos 32a)