Sayyiduna Abdullah (may Allah be pleased with him) narrates: A man presented himself before the Prophet (peace and blessings be upon him) and said: O Messenger of Allah! How can I know whether I have done good or I have done evil? The Prophet (peace and blessings be upon him) said: When you hear your neighbor saying that you have done good, then it means you have done good, and when you hear those people saying that you have done evil, then it means you have done evil.
Hadith Referenceصحیح ابن حبان / كتاب البر والإحسان / 526
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - المصدر نفسه.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط مسلم، رجاله رجال الشيخين غير محمد بن عبد الأعلى فمن رجال مسلم، وهو مكرر ما قبله.