Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates: Two men sneezed in the presence of the Prophet (peace and blessings be upon him). He responded to one of them (the narrator is unsure about a word here) and did not respond to the other. It was said to him: Two men sneezed. You responded to one of them and did not respond to the other? The Prophet (peace and blessings be upon him) said: He praised Allah, and the other did not praise Him.
Hadith Referenceصحیح ابن حبان / كتاب البر والإحسان / 601
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح: ق، وهو مكرر ما قبله.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط البخاري، رجاله ثقات رجال الشيخين غير مسدد بن مسرهد فمن رجال البخاري. ابن أبي عدي: هو محمد بن إبراهيم.