Berachos 3b - Part 5

The gemara previously stated that King David arose at midnight. The gemara now asks, how could King David have known when midnight was precisely? For we know that even Moshe did not know the exact time of midnight. The gemara proves that Moshe did not know exactly when midnight was from the fact that Moshe says in Shemos 11, "around midnight I will go out into Mitzrayim". Why does Moshe say "around" midnight? If you say it is because Hashem Himself said that, are there any doubts in the heavens? So, the gemara says, it must be that Hashem said "at midnight" and Moshe said "around midnight". Thus, you see, that Moshe himself did not know exactly when midnight was. So, how did King David know?

Answer #1: King David had a sign that told him when midnight was.

The gemara proves this answer from a statement of Rav Acha Bar Bizna in the name of R' Shimon Chasidah who said as follows:

There was a harp that hung above the bed of King David. When midnight came a northern wind would blow and the harp would play on its own. Immediately he would arise and learn torah until dawn. At dawn, the chachmei yisrael would come to him and say, "our master the king, your nation Israel needs parnassah". He said to them, "go and make parnassah one from the other". They said to him, "the fistful cannot satisfy the lion and a pit cannot be filled from its surrounding heap". He said to them, "go and stick your hand in the spoils". Immediately, they went to seek the advice of Achitofel, the sanhedrin, and the urim v'tumim.