I was with my father, sitting beside him, in the company of Abdullah bin Masud. My father asked him, "Did you hear the Messenger of Allah ﷺ say, 'Regret is repentance'?"He replied, "Yes, I heard the Messenger of Allah ﷺ say it."
كنت مع أبي وأنا إلى جنبه عند عبد الله بن مسعود فقال له أبي: أسمعت من رسول الله ﷺ يقول: الندم توبة؟ فقال: نعم سمعت رسول الله ﷺ.
Tayalisi (380) narrated it from Zuhayr bin Muawiya, and Ahmad (4012) narrated it through Furat, both of them from Abdul-Kareem Jazari, from Ziyad bin Jarrah (who is not Ibn Abu Maryam), from Abdullah bin Maqil, and he related it. The wording given is Tayalisi's, and its chain is sahih.Ibn Majah (4252), Ahmad (3568), and Hakim (4/243) all narrated it through Sufyan bin Uyayna, from Abdul-Kareem Jazari, who said, "Ziyad bin Abu Maryam told me, from Abdullah bin Maqil bin Muqrin," and he related something similar. Hakim said, "This is a hadith with a sahih chain."I say, it is as he said. Ziyad bin Abu Maryam is Jazari, whom Ajli, Ibn Hibban, and Daraqutni deemed trustworthy. But several critics have stated that saying "Ziyad bin Abu Maryam" in this chain is an error, and that he is actually Ziyad bin Jarrah Jazari, who is also trustworthy. So the chain is sahih, and it revolves between two trustworthy narrators.As for what has been narrated from Abu Ubayda bin Abdullah bin Masud, from his father, who said, the Messenger of Allah ﷺ said, "One who repents from sin is like one who has no sin," the correct view is that this hadith is the hadith of Abdullah bin Maqil from Ibn Masud.Ibn Majah (4250), Tabarani in Kabir (10/185), and Bayhaqi in Kubra (10/154) all narrated it through Waheeb bin Khalid, who said, "Mamar told us, from Abdul-Kareem Jazari, from Abu Ubayda bin Abdullah bin Masud, from his father," and he related it.But Abu Ubayda never heard from his father, so this narration is an error. The correct version is what Abdul-Kareem Jazari narrated, from Ziyad, from Abdullah bin Maqil, who said, "I entered along with my father upon Ibn Masud," as in the hadith mentioned earlier. This is also what Abu Hatim, Daraqutni, Bayhaqi, and Khatib have said. See Ilal Ibn Abu Hatim (1918), Ilal Daraqutni (5/297), and Muwaddih li-Awham Jam wal-Tafriq (1/258).As for the wording of the hadith, "One who repents from sin is like one who has no sin," it has also been narrated from other companions, including what was narrated from Ibn Abu Saad Ansari, from his father, that the Messenger of Allah ﷺ said, "Remorse is repentance, and one who repents from sin is like one who has no sin."Tabarani narrated it in Kabir (22/306) through Duhaym, who said, "Ibn Abu Fudayk told us, Yahya bin Abu Khalid told us, from Ibn Abu Saad Ansari, from his father," and he related it. Abu Hatim said, "Yahya bin Abu Khalid is unknown, and Ibn Abu Saad is likewise, and this hadith is daif." Ilal Hadith (1889)The hadith has also been narrated from Ibn Abbas, Anas, and others, all of which contain defects, but taken together they indicate that it has a basis.As for his saying ﷺ, "Remorse is repentance," this is sahih and established.