Halakhah sa Mga Bilang 32:14: Sefer Chasidim

“In all thy ways acknowledge Him” (Prov. 3:6). Let every God-fearing man, when angered because of transgressors, weigh his anger, so that his mind is (remains) settled. Let him learn from Moses, our teacher, when he became angry with the children of Reuben he said, “a brood of simple men” (Num. 32:14). Therefore, his grandson became a servant to the idol of Micah,¹J. T. Berakoth 9:2. even though he became angry for the sake of heaven, nevertheless, everything requires a balance. And so with festivities that involve the performance of a (religious) command, let him not remove anger completely. (This refers to) those who perform a command with overmuch gaiety, let his anger not be distant.²Berakoth 30b.