Sahih Bukhari
Virtues and Merits of the Prophet (pbuh) and his Companions
Volume: 004 / Book Number: 056 / Hadith Number: 797
Narrated Zainab bint Jahsh:
That the Prophet came to her in a state of fear saying, "None has the right to be worshiped but Allah! Woe to the Arabs because of evil that has come near. Today a hole has been made in the wall of Gog and Magog as large as this." pointing with two of his fingers making a circle. Zainab said, "I said, 'O Allah's Apostle! Shall we be destroyed though amongst us there are pious people? ' He said, 'Yes, if evil increases."
Narrated Um Salama: The Prophet woke up and said, "Glorified be Allah: What great (how many) treasures have been sent down, and what great (how many ) afflictions have been sent down!"