Bava Metzia 33 - Suffering of Sentient Beings
One should protect living beings from suffering, as evidenced by the angel rebuking Balaam for striking his she-ass .
But consider this ruling: if one has a choice whether to unload his friend's animal, which is suffering under a load, or to load his enemy's one - he should load his enemy's, in order to subdue his own Evil Inclination. What about the animal suffering? - Subduing one's Evil Inclination is more important.
Retrieving his lost article takes precedence over the lost article of his father or his teacher. A lost article of his teacher takes precedence over that of his father, unless his father is also a Sage.
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