It is one of the etiquettes of ablution to send blessings upon the Prophet, peace be upon him, after washing each limb; for Sahl ibn Sa'd, may Allah be pleased with him, said that the Prophet, peace be upon him, said: "There is no ablution for one who does not send blessings upon the Prophet, peace be upon him," as mentioned in Al-Mu'jam Al-Kabir 6: 121, and Al-Suyuti indicated its weakness. See: I'laa Al-Sunan 1: 111. See: Tabyin Al-Haqaiq 1: 6-7, Majma' Al-Anhar 1: 16, Bada'i' Al-Sana'i' 1: 23-24, and Al-Talimat Al-Mardiya on Al-Hadiya Al-Ala'iya p. 25.