The Apostle of Allah (peace_be_upon_him) said:
The best day on which the sun has risen is friday; on it Adam was created, on it he was expelled (from Paradise), on it his contrition was accepted, on it he died, and on it the Last Hour will take place. On friday every beast is on the lookout from dawn to sunrise in fear of the Last Hour, but not jinn and men, and it contains a time at which no Muslim prays and asks anything from Allah but He will give it to him.
Ka'b said: That is one day every year. So I said: It is on every friday. Ka'b read the Torah and said: The Apostle of Allah (peace_be_upon_him) has spoken the truth.
AbuHurayrah said: I met Abdullah ibn Salam and told him of my meeting with Ka'b. Abdullah ibn Salam said: I know what time it is. AbuHurayrah said: I asked him to tell me about it. Abdullah ibn Salam said: It is at the very end of friday. I asked: How can it be when the Apostle of Allah (peace_be_upon_him) has said: "No Muslim finds it while he is praying...." and this is the moment when no prayer is offered.?
Abdullah ibn Salam said: Has the Apostle of Allah (peace_be_upon_him) not said: "If anyone is seated waiting for the prayer, he is engaged in the prayer until he observes it." I said: Yes, it is so.
Bukhari (Book #3, Hadith #1041)