كُلُّ بَنِي آدَمَ خَطَّاءٌ، وَخَيْرُ الْخَطَّائِينَ التَّوَّابُونَ (Tirmidhi)
Translation: All children of Adam are prone to error, and the best of those who err are those who repeatedly repent.
خَطَّاءٌ — one who errs repeatedly; الْخَطَّائِينَ — those who err; التَّوَّابُونَ — those who often repent.
Brief grammar: In كُلُّ بَنِي آدَمَ, كُلُّ conveys universality. خَطَّاءٌ is the predicate; التَّوَّابُونَ is a sound masculine plural. تَوَّاب suggests repeatedly returning in repentance.
The statement does not excuse persistence in wrongdoing. It praises returning to Allah after error, rather than making error a habit to defend.