Rav Yisrael Lipkin of Salant


At twilight one evening he was seen gazing at the sky in order to determine the exact moment of nightfall.  It turned out that his doctors had ordered him to rest for three days without learning, and R’ Yisrael carried out the instructions to the letter.  At the end of the third day, he set out to determine the exact moment of nightfall, for “Just as it is forbidden to delay the study of Torah of even one moment, so is it forbidden to begin one moment too early, because of the obligation of guarding one’s health.”


From Sparks of Mussar by R Chaim Ephraim Zaitchik