Tafsir of Al-Ahzab 33:11

How the Believers were tested, and the Position of the Hypocrites during the Battle of Al-Khandaq Allah tells,

هنالك ابتلي المومنون وزلزلوا زلزاﻻ شديدا

There, the believers were tried and shaken with a mighty shaking. Allah tells us what happened when the Confederates surrounded Al-Madinah and the Muslims were besieged and found themselves in straitened circumstances, with the Messenger of Allah in their midst. They were tried and tested, and were shaken with a mighty shaking. At this time hypocrisy emerged, and those in whose hearts was a disease spoke about what they really felt

وإذ يقول المنافقون والذين في قلوبهم مرض ما وعدنا الله ورسوله إﻻ غرورا