to do something because you feel sympathy for someone She stood there shivering until Claudia took pity on her and put her sweater around the child's shoulders.
Also, have pity on. Show compassion or mercy to, as in Take pity on the cook and eat that last piece of cake, or, as Miles Coverdale's 1535 translation of the Bible has it (Job 19:21), "Have pity upon me, have pity upon me, O ye, my friends." This idiom may be used half-jokingly, as in the first example, or seriously. [Late 1200s]