It is narrated from Sayyidah Aishah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: "Caution is of no avail against destiny, while supplication benefits against what has already come down (of afflictions) and what has not yet come down. And indeed, when an affliction comes down, supplication meets it, and the two wrestle with each other until the Day of Resurrection." This hadith is sahih al-isnad (its chain is authentic), but the two Shaykhs (Bukhari and Muslim) did not record it.