Sayyidah Aishah al-Siddiqah (may Allah be pleased with her) narrates: The Prophet (peace and blessings be upon him) was on a journey, and I felt a sense of dread during the night. The Prophet (peace and blessings be upon him) asked: "What is the matter with you?" I said: "We are in this place on a dark night, and I fear for you." The Prophet (peace and blessings be upon him) said: "Not at all! Allah Almighty will send us a man who loves Allah and His Messenger; he will keep watch over us for the rest of the night." Sayyidah Aishah (may Allah be pleased with her) narrates: While we were in that state, I saw someone coming towards us. The Prophet (peace and blessings be upon him) asked: "Who is this?" He said: "I am Sa'd bin Malik. I have come to keep watch over you for the rest of the night." Then the Prophet (peace and blessings be upon him) laid down his head and slept. (Al-Haythami says:) I say: Part of this narration is mentioned in the Sahih.
Al-Tabarani recorded it in al-Mu'jam al-Awsat. Its chain contains Abu Ja'far al-Ashja'i, whom I do not know. The rest of its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 14867