The following story is recorded in An Angel Among Men, pg 130-133:
Dr. Nachum Arieli recalled:
The Rav (Rav Kook) and my father studied the Talmud together at a set time every day ... The Rav made it his practice never to lock the doors of his house, not the front door nor the door to his study. His home was open to visitors day and night, with no set reception hours... Yet, in this "open house" the door to the Rav's study was locked a few hours every morning. It was an immutable rule. This was when the Rav would study the Talmud with my father.
...
On one of those wonderful days the two scholars forgot to lock the door to the Rav's study. They were so absorbed in their studies that they failed to notice that the door had opened and Eliezer Ben-Yehudah [the "father" of modern Hebrew] had entered. When they finally noticed him, neither said a word. Ben-Yehudah, however, began asking the Rav numerous questions on linguistics, [in search of] the origins and explanations of words. The Rav was like a perennial spring, deciphering the origins of words based on sources from both the revealed and esoteric portions of the Torah. It seemed as if he was scanning the lines of text right before his eyes. He wove ideas and words together like one of the world's foremost philologists, until Ben-Yehudah's questions ceased. The Rav still had more to say, but once the questions stopped, the Rav contained himself. He had only one more thing to say: "Mr. Ben-Yehudah, perhaps the time has come for you to repent?" Ben-Yehudah replied, "Perhaps." He said no more; with that he took his leave.
The two scholars returned to their studies as if nothing had happened, like a rock thrown into the sea. The rock creates a hole in the water, causing it to rise like a fountain, but then the water returns to its original state, as if nothing happened.
This whole episode occurred on Friday morning, the second day of Chanukah, 5683. That very evening, ten to fifteen hours after his meeting with Rav Kook, Eliezer Ben-Yehudah died. My father claimed that Ben-Yehudah's response - "Perhaps" - had the status of "thoughts of repentance," which are considered like actual repentance (see Kiddushin 49b).
