Majma al-Zawaid — Hadith 12189

Sayyiduna Sa'd bin Abi Waqqas (may Allah be pleased with him) narrates: I heard the Prophet (peace and blessings be upon him) say: "Indeed Islam began as a stranger, and soon it will again become a stranger as it began. So glad tidings at that time to the strangers, when (other) people have become corrupt. By the One in whose hand is the soul of Abu al-Qasim, faith will retreat to the area between these two mosques just as a snake retreats to its hole."
Ahmad, al-Bazzar and Abu Ya'la recorded it, and the narrators of Ahmad and Abu Ya'la are the narrators of the Sahih.