The Messenger of Allah ﷺ said, "No one persists in sin who seeks forgiveness, even if he does so seventy times in a day."
حدثنا حسين بن يزيد الكوفي حدثنا أبو يحيى الحماني حدثنا عثمان بن واقد عن أبي نصيرة عن مولى لأبي بكر
قال رسول الله ﷺ ما أصر من استغفر ولو فعله في اليوم سبعين مرة
Hasan. Abu Dawud narrated it in Witr, chapter on seeking forgiveness, hadith no. 1514, from the hadith of Uthman bin Waqid, with this wording, from a freed slave of Abu Bakr, who is unknown (per Taqrib). The hadith has an isolated hasan corroborating witness in Tabarani's Dua, no. 1797, and with it the hadith is hasan.