Once Imaam Abu Dawood (rahimahullah), who’s “Sunan” is one of the six classical books of hadeeth, was on board a ship. He heard a person on the shore sneezing and saying “Alhamdulillah” (all praise is due to Allah). So he hired a rowing boat for one dirham (silver coin) and went to shore to reply to this person by saying “Yarhamukallah” (may Allah have mercy on you), as is the sunnah of Rasulullah (sallallahu ‘alaihi wasallam). When he was asked about this action of his, he replied: “It is possible that this person who sneezed is a person whose supplication is accepted by Allah Ta‘ala.” When the people on board the ship fell asleep, they heard someone calling out: “O people of the ship! Surely Abu Dawood purchased paradise from Allah Ta‘ala for one dirham.” (Risaalatul Mustarshideen pg. 157)
Lesson: Despite the great services which he rendered to Islam, a “small” sunnah like this became the means of his entry into Jannah. We cannot regard any good deed as small or any sin as trivial. Every good deed has the potential of securing us a place in Jannah, while every sin has the possibility of landing us into eternal ruin and misery.