Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: When this was revealed to the Prophet (peace and blessings be upon him): "When the help of Allah and the victory come," whenever the Prophet (peace and blessings be upon him) recited it, he would say the takbir and go into bowing, and he would say: "Subhanakallahumma wa bihamdika, Allahummaghfir li, innaka antat-Tawwabur-Rahim (Glory be to You, O Allah, and praise be to You; O Allah, forgive me, indeed You are the Accepter of repentance, the Most Merciful)."
Imam Ahmad, Imam Abu Ya'la, Imam al-Bazzar, and Imam al-Tabarani in al-Mu'jam al-Awsat recorded it. In the chains of the three it is mentioned that Abu Ubaydah narrated it from his father, although he did not hear from his father. The narrators of al-Tabarani are the narrators of the Sahih, except for the narrator Hammad, who is thiqah (trustworthy) but suffered from confusion (ikhtilat).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2772