From him (the Companion, i.e. Sayyiduna Abu Umamah (may Allah be pleased with him)), in "al-Mu'jam al-Saghir",
this report is recorded: The Prophet (peace and blessings be upon him) said: When a Muslim, while performing ablution, washes his hands, this becomes an expiation for the (sins) that his hand did; when he washes his face, this becomes an expiation for the things his eyes looked at; when he wipes his head, this becomes an expiation for the things his ears heard; and when he washes his feet, this becomes an expiation for the sins towards which he walked on his feet. Then when he stands for the prayer, it (i.e. the prayer) becomes a source of virtue for him. There is disagreement about using Abu Ghalib as proof; the rest of the narrators of this report are thiqat (trustworthy). Imam al-Tirmidhi declared a report narrated through Abu Ghalib hasan (good), and he also declared a report narrated through him "sahih" (authentic).
Imam Ahmad recorded this report with a "sahih" chain, adding these words: The Prophet (peace and blessings be upon him) said: "Ablution becomes an expiation for his sins before it, and then the prayer becomes nafl for him (i.e. a means of extra reward)." He also recorded this report with another "sahih" chain, with these words: "When he performs ablution as he has been commanded."
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1127