Muwatta Malik 1828
موطأ مالك#1828Da'ifMalik related to me that he heard that Abdullah ibn Masud used to say, "The slave continues to lie and a black spot grows in his heart until all his heart becomes black. Then he is written, in Allah's sight, among the liars
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Salim al-HilaliMauquf Daif
In-book reference: 56:18