It is narrated from Hazrat Suhaib (may Allah be pleased with him) that once I passed by the Prophet Muhammad (peace and blessings be upon him) while he was praying. I greeted him with salam, and he replied to me by signaling with his finger.
Hadith Referenceمسند احمد / تتمہ مُسْنَدِ الْكُوفِيِّينَ / 18931
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد حسن