Rav Tzvi Pesach Frank (born 5633/1873), chief Rav of Yerushalayim and mechaber of Har Tzvi, used to tell a story from his childhood that made a deep impression on him all his life:
“When I was a child in Kovna and it was the beginning of Chodesh Elul, I followed all the adults into the Bais Medrash to hear the derosha of Rav Yisrael Salanter zt”l. The Bais Medrash was packed and, finding nowhere else to sit, I sat myself down on the steps leading to the Aron Kodesh. In the middle of Rav Yisrael Salanter’s derosha he called out,
‘Yidden! Mir gefinen zich itzter in Chodesh Elul – macht teshuva! – Fellows Jews! We find ourselves in the midst of the month of Elul – do teshuva!’
As he said these words, he fainted and fell at the foot of the bima! I saw him lying there, pale as a ghost; he looked like he had died. The sight of such a thing has left its mark on me all my life!” (Kodesh Elul Chapter 3, cited from Bais Va’ad II p. 33)