Allah says in the Quran Are they waiting for anything except the hour, to come to them suddenly? But its signs have already come! (Surah Muhammad:18)
The Prophet Muhammad (SAW), among other things, came to warn us of a time when the truth would be known and when the thoughts and intentions of the heart would be revealed. He earnestly proclaimed as inevitable a day when accounts would be settled and scales would be balanced.
This lecture goes through some of the signs that will precede the day when Allah will gather all beings to stand before Him in account.