Sahih Muslim
The Book Giving Description of the Day of Judgement, Paradise and Hell (Kitab Sifat Al-Qiyamah wal Janna wan-Nar)
Book Number: 039 / Hadith Number: 6744
Ka'b reported that Allah's Messenger (may peace be upon him) said that the similitude of a believer is that of a standing crop in a field which is shaken by wind and then it comes to its original position but it stands at its roots. The similitude of a non-believer is that of a cypress tree which stands on its roots and nothing shakes it but it is uprooted (with) one (violent stroke).