Muwatta Malik 66
موطأ مالك#66Sahihوَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " اسْتَقِيمُوا وَلَنْ تُحْصُوا وَاعْمَلُوا وَخَيْرُ أَعْمَالِكُمُ الصَّلاَةُ وَلاَ يُحَافِظُ عَلَى الْوُضُوءِ إِلاَّ مُؤْمِنٌ " .
Yahya related to me from Malik that he had heard that the Messenger of Allah, may Allah bless him and grant him peace, said, "Try to go straight, although you will not be able to do so. Act, and the best of your actions is the prayer. And only a mumin is constant in his wudu
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 2:35