Hadith: Shall I not tell you something by which Allah erases sins and elevates ranks (in Paradise)? The Companions said: Certainly, O Messenger of Allah! He said: Performing the ablution properly even in difficulty, increasing attendance of prayer in the mosque, and waiting for the next prayer after observing one prayer; and this is Jihad

عن أبي هريرة قال: قال رسول الله صلى الله عليه وسلم : «ألا أَدُلُّكُم على ما يَمْحُو الله به الخطايا ويرفع به الدرَجات؟» قالوا: بلى، يا رسول الله، قال: «إِسْبَاغُ الوُضُوء على المَكَارِه، وكَثْرَةُ الخُطَا إلى المساجد، وانتظارُ الصلاة بعد الصلاة فذلِكُم الرِّباط».
[صحيح] - [رواه مسلم]

Abu Hurayrah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "Shall I not tell you something by which Allah erases sins and elevates ranks (in Paradise)?" The Companions said: "Certainly, O Messenger of Allah." He said: "Performing the ablution properly even in difficulty, increasing attendance of prayer in the mosque, and waiting for the next prayer after observing one prayer; and this is jihad."
Sahih/Authentic. - [Muslim]

Explanation

The Prophet (may Allah's peace and blessings be upon him) presented an offer to his Companions. He already knew what their answer would be. This is a good teaching method. He used to present issues as questions so that the people would pay more attention to what was coming. So the Prophet (may Allah's peace and blessings be upon him) said: "Shall I not tell you something by which Allah effaces the sins and elevates ranks (in Paradise)?" The Companions said: "Certainly, O Messenger of Allah." In other words: tell us as we would love to know about what will increase our ranks and erase our sins. He said: Firstly: Performing the ablution properly even in difficulty, as during the days of winter, when the water is cold. So if a person completes his ablution given this hardship, this is proof of his completeness of faith. Thereby, Allah will raise his rank and erase his sins. Secondly: Attending the five daily prayers in the mosque, even if it is far. Thirdly: Having the desire to pray. Every time he finishes a prayer, his heart is attached to the next one. This is proof of his faith, love, and desire to pray more of these great prayers. If he awaits prayer after prayer, this is among the reasons for which Allah raises his rank and erases his sins. Then the Prophet informed that constant commitment to purification (ablution), prayer, and worship is like Jihad for the sake of Allah.