Layth here is Ibn Abi Sulaym, about whom the critics have reservations. Mudrik is Ibn ʿAmarah ibn ʿUqbah; a number of scholars transmitted from him, Ibn Hibban counted him among the trustworthy in al-Thiqat, and Ibn Hajar includes him in Taʿjil al-manfaʿah. Taken together, all the available chains show that the phrase “Allahumma! tahhirni … (O Allah, purify me …)” is never reported—even once—as a supplication recited after rising from bowing. Therefore, to list it among the adhkar of that posture, as Ibn al-Qayyim does in Zad al-Maʿad and others follow him, is unsound; take note. The report is supported, however, by a corroborating narration from Ibn ʿAbbas: when the Prophet would say “Samiʿa Allahu liman hamidah” (Allah hears those who praise Him) he added, “Allahumma Rabbana! laka al-hamd milʾa al-samawat … ” and so on. Muslim (2/48), Abu ʿAwanah (2/176), al-Nasaʾi (1/162), al-Tahawi (1/140), al-Bayhaqi (2/94), and Ahmad (1/370) record it through Hisham ibn Hassan → Qays ibn Saʿd → ʿAtaʾ → Ibn ʿAbbas. Ahmad (1/270) also narrates it via Hammad ibn Salamah → Qays ibn Saʿd → Saʿid ibn Jubayr → Ibn ʿAbbas, and again (1/275, 333) through other routes from Saʿid ibn Jubayr. Muslim, Abu ʿAwanah (2/177), and al-Bayhaqi further transmit it through Hushaym ibn Bashir → Hisham ibn Hassan with the additional words: “Ahl al-thanaʾ wa-l-majd (Lord of praise and glory), none can withhold what You give, none can give what You withhold, and the wealth of the wealthy avails them nothing against You.”