Sahih Muslim Book 40, Hadith Number 6843.

Chapter : Pertaining to the destruction of the world and assembling on the day of Resurrection.

This hadith has been narrated through five different chains of transmitters and all of them are narrated on the authority of Mustaurid, brother of Bani Fihr, that Allah’s Messenger (may peace be upon him) said: By Allah, this world (is so insignificant in comparison) to the Hereafter that if one of you should dip his finger (and while saying this Yahya pointed with his forefinger) in the ocean and then he should see as to what has stuck to it. This hadith has been narrated through another chain of transmitters also but with a slight variation of wording.