Ali on Tawbah: Repentance is by deeds, not merely words

Musa ibn Abi Habib reported: Ali ibn Husayn, may Allah be pleased with him, said, “Verily, repentance is only by action and turning away from the matter. Repentance is not by speech alone.”

Source: al-Tawbah li-Ibn Abī al-Dunyā 57

عَنْ مُوسَى بْن أَبِي حَبِيبٍ الطَّائِفِيُّ عَنْ عَلِيِّ بْنِ حُسَيْنٍ رضي الله عنه قَالَ إِنَّمَا التَّوْبَةُ بِالْعَمَلِ وَالرُّجُوعِ مِنَ الْأَمْرِ وَلَيْسَتِ التَّوْبَةُ بِالْكَلَامِ

57 التوبة لابن أبي الدنيا