The Excellence of Making Wudhoo and Praying according to the Sunnah
Abu Ayyub (may Allaah be pleased with him) said: “I heard the Messenger of Allaah (sallahAllaahu alayhi wasallam) saying, “Whoever makes wudhoo as commanded, and prays as commanded: will have his past sins forgiven.” 
SubhanaAllaah look at this great reward for actions (wudhoo & prayer) we do everyday numerous times! All we need to do is have the right intention and perform them as per the Sunnah.
Note: this hadeeth and others like it which mention the expiation of sins, what is meant is the minor sins, and that one avoids the major ones and repents from those already committed.
1. Sunan an-Nasaa’ee, chapter: The reward of the one who makes wudhoo as commanded, and Sunan Ibn Maajah, graded as Saheeh by Shaykh Al-Albaanee.