Imam Malik's Muwatta, Chapter: Itikaf in Ramadan

Ziyad related to me from Malik that he had heard a man he trusted of the people of knowledge say, "The Messenger of Allah, may Allah bless him and grant him peace, was shown the lifespans of the people (who had gone) before him, or what Allah willed of that, and it was as if the lives of the people of his community had become too short for them to be able to do as many good actions as others before them had been able to do with their long lives, so Allah gave him Laylat al-Qadr, which is better than a thousand months."