הרב יצחק בן אלישיב

Rabbi Yitzchak ben Eliashiv was an amora who appears in tractate Taanit. The Gemara there depicts him as a sage whose tefillah was answered, recording how Rabbi Mani would attend him and bring his troubles before him. When Rabbi Mani complained that his wealthy in-laws were causing him distress, Rabbi Yitzchak ben Eliashiv prayed that they become poor, and they grew poor; when Rabbi Mani then said they were now pressing upon him in their need, he prayed that they become wealthy again, and they grew wealthy.

The Gemara also brings two students who stood before him and asked that he pray for them to gain great wisdom. He answered that this power had once been with him but he had sent it away, indicating a measure of such ability that he no longer chose to exercise. These passages present him as a figure associated with the effectiveness of prayer.