The tradition mentioned above has also been transmitted by Umm Salamah through a different chain of narrators to the same effect. This version has: He who disapproves is guiltless, and he who disapproves is safe. Qatadah said: it means one who feels its disapproval in his heart, and one who expresses disapproval in his heart.
Explanation & Benefits
Shaykh Umar Farooq Saeedi
Benefits and Issues:
The meaning of disapproving with the heart is that such a person should have the resolve that if not today, then tomorrow—whenever possible—I will certainly eradicate this evil.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 4761