Shimon, the second son of Jacob and Leah and the progenitor of the Israelite tribe of Shimon, was born on Tevet 21 (according to another opinion, on Tevet 28), of the year 2194 from creation (1567 BCE), nine years after Jacob's arrival in Charan.
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On December 23 (21 Teves), 1690, strong earthquakes rattled the city of Ancona, Italy, causing numerous structures to collapse and placing its inhabitants in mortal danger. Miraculously, the Jewish quarter was spared, suffering the collapse of only one house. In commemoration of this event, the local Jewish community established that date as a day of celebration and song, while the previous day—20 Teves—would be marked yearly by fasting and charity (Or Boker, p. 48a).
By the time Moses returned to the scene, his people had hit an all-time low.
They worshipped idols, spoke slanderously of each other, and had wandered very far from the path of their forefathers.
Perhaps he should have told them off, saying, “Repent, sinners, lest you perish altogether!”
But he didn’t. Instead, he told them how G‑d cared for them and felt their suffering, how He would bring about miracles, freedom and a wondrous future out of His love for them.
As for rebuke, Moses saved that for G‑d. “Why have You mistreated Your people?!” he demanded.
If you don’t like the other guy’s lifestyle, do him a favor, lend him a hand.
Once you’ve brought a few miracles into his life, then you can urge him to chuck his bad habits.