Majma al-Zawaid — Hadith 1124

Shahr bin Hawshab narrates: Sayyiduna Abu Umamah (may Allah be pleased with him) told me that the Prophet (peace and blessings be upon him) said: "Whoever gets up to perform ablution, intending to offer the prayer, and then washes his palms, every sin of his palms (descends, i.e.) leaves with the first drop; when he rinses his mouth, puts water into his nose and cleans his nose, every sin of his tongue and lips leaves with the first drop; when he washes his face, every sin of his hearing and sight leaves with the first drop; when he washes both his arms up to the elbows and both his feet up to the ankles, he becomes free of every sin just as he was on the day his mother gave birth to him. Then when he stands to offer the prayer, Allah Almighty raises his rank, and if he remains seated (i.e. even if he does not offer the prayer), he sits in a state of being salim (i.e. free of sins)."
Imam Ahmad and Imam al-Tabarani (in al-Mu'jam al-Kabir and al-Mu'jam al-Awsat) recorded this report. Imam Ahmad's chain states that Abd al-Hamid bin Bahram narrated it from Shahr; there is disagreement about using the two of them as proof, but the correct view is that both are thiqah (trustworthy), and the criticism made of them is not a cause of disparagement.