Ibrāhīm passed judgment against a man on the strength of Rabiʿah’s personal opinion, so I informed him of a report from the Messenger of Allah ﷺ that ran contrary to his ruling.
Saʿd thereupon said to Rabiʿah, “This is Ibn Abī Dhīb, and in my estimation he is trustworthy; he is relating from the Prophet ﷺ something that conflicts with the sentence I have issued.”
Rabiʿah replied, “You exercised ijtihād, and your verdict has already taken effect.”
Saʿd protested, “How astonishing! Shall I uphold the decree of Saʿd son of Umm Saʿd and set aside a ruling delivered by the Messenger of Allah ﷺ? Rather, I shall revoke Saʿd’s decision and enforce the judgment of the Messenger of Allah ﷺ.”
He then ordered the written record of the case to be brought, tore it up, and ruled in favor of the party who had previously been judged against.

Al-Bukhārī related: Sahl narrated to me, Abū Salamah narrated to us, and Abū al-Haytham Muḥammad ibn Ḥafṣ informed me, saying:
“Saʿd was once in the company of Ibn Hishām al-Makhzūmī, the governor of Medina, when a dispute arose before him between a son of Muḥammad ibn Maslamah and a man from Banū Ḥārithah. The son of Muḥammad declared, ‘I am the son of the slayer of Kaʿb ibn al-Ashraf!’ The Ḥārithī retorted, ‘By Allah, he was killed only treacherously.’
“Saʿd waited for the governor to rebuke that remark, but he did not, and the two litigants departed. Later, when Saʿd himself was appointed judge, he said to his servant, ‘I give Allah my solemn pledge: if that Ḥārithī escapes from you, I shall make you smart for it.’
“Shuʿbah said: I prayed the dawn prayer with him, then brought the man to Saʿd. The moment Saʿd saw him he ripped open his tunic and said, ‘Are you the one who claimed that Kaʿb ibn al-Ashraf was killed deceitfully?’ He then administered 150 lashes, shaved his head and beard, and declared, ‘By Allah, so long as I possess authority over you I shall straighten you out with the whip.’ (1)

Yaʿqūb ibn Ibrāhīm ibn Saʿd narrated on the authority of his father: “A group of Qur’an reciters came to visit him during his illness—among them Ibn Hurmuz and Ṣāliḥ, the freedman of al-Tawʾamah. Ibn Hurmuz’s eyes filled with tears, so Saʿd asked, ‘What makes you weep?’
“He replied, ‘By Allah, it is as though I can already hear someone tomorrow crying, “Alas for the champion of truth—Saʿd is no more!”’
“Saʿd said, ‘By Allah, if such words are uttered, they will be true; for I have not heeded the blame of any blamer for Allah’s sake these forty years.’ He then added, ‘Do you not know that you—meaning the Qur’an—are the most beloved of His creation to me?’”

Ibrāhīm ibn Saʿd and a number of others stated that Saʿd died in 125 AH. Yaʿqūb ibn Ibrāhīm, Khalīfah, and others said he died in 127 AH, while another view places his death in 126 AH.