Lifelong Goal

The Gemara quotes the fascinating story surrounding the death of Rav Chisda.
It was time for Rav Chisda to return his precious soul to his Creator. However, the Malach HaMaves could not find any time that Rav Chisda was not learning; his nonstop Torah study made him impervious to death. The agent of the Malach HaMaves sat on a pillar that supported the beis midrash where Rav Chisda was studying. The pillar snapped and the resultant noise startled Rav Chisda. He momentarily stopped learning and thus expired.
The Ben Ish Chai points out that a similar story occurred to Dovid HaMelech. He wonders why the Gemara, in attempting to prove its point, didn’t quote the story of Dovid HaMelech instead. He explains that this story demonstrates the awesome power of Torah learning to protect a person from death. Had the Gemara quoted the similar story with Dovid HaMelech, people could have discounted the story as irrelevant to them. After all, Dovid was a king and a prophet—perhaps it was Torah in conjunction with those merits that protected his life. Moreover, Dovid HaMelech died in Eretz Yisrael, on Shabbos. Perhaps Shabbos and Eretz Yisrael provided added protection to Dovid HaMelech. The Gemara therefore quotes the story with Rav Chisda to demonstrate that it was the power of Torah alone that protected Rav Chisda. This is evident because Rav Chisda was neither a king nor a prophet and he died in Bavel on a weekday.