Yahya ibn Ma'een said:
ما رأيت على رجل خطأ إلا سترته
"I never saw a mistake in a person except that I would cover it up for him."
["Siyar A'lam An-Nubala", 11/83].
Hasan al-Basri (d.110 A.H.) said:
‘Statements cannot be correct except with actions; Statements and actions cannot be correct except with an intention; and statements, actions and an intention cannot be correct except according to the Sunnah.’
[From ‘Sharh Usool I’tiqaad Ahl-us-Sunnah’ al –Laalkaee 2/57]