When Herod killed out all the sages (Bava Batra 3b) he spares Bava ben Buta. I would like to know if any commentaries explain why Herod chose to spare this sage in particular.
In Ben Yehoyada, the Ben Ish Chai writes that Bava ben Buta was spared by Herod because he was known to be someone who doesn't hold a grudge or take revenge. He would forgive people who wronged him and he would even act kindly to those who had harmed him. The source text for this explanation is a story in Nedarim (66b). A husband got angry at his wife for mistakenly bringing him two melons instead of two candles. He said to her, "smash those on the head of bava. He was, of course, referring to the Aramaic word for fence, but she misunderstood him again and thought that he was referring to the head of Bava ben Buta. She then went and actually smashed two melons over Bava Ben Buta's head! When Bava Ben Buta realized that she misunderstood her husband and wasn't acting out of malice, he gave her a blessing that she should have sons who are scholars just like him.
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Found an online Hebrew PDF/ sefer "פתחו שערים -- בבא בן בוטא" (page 266) that writes:
הורדוס רצח את כל החכמים אבל את בבא בן בוטא לא יכול היה להרשות לעצמו להרוג. הוא הכיר בחכמתו הרבה והשאיר אותו בחיים כדי שיוכל ליטול עצה ממנו. אך ברשעותו הרבה הוא לא הניח לו לחלוטין אלא ניקר את עיניו.
Herod murdered all the sages but could not bring himself to kill Bava ben Buta. Herod recognized Bava ben Buta's great wisdom and left him alive so that he could take advice from him. He did not let him completely off the hook, rather he poked out at his eyes.
I couldn't tell if this is his own commentary or if it's derived from a different commentary.