Sayyiduna al-Nu'man bin Bashir (may Allah be pleased with him) says: When we prayed behind the Prophet (peace and blessings be upon him) and he said 'Sami'a Allahu liman hamidah' (Allah hears the one who praises Him) and stood up from bowing, none of us would bend his back until he saw that the Prophet (peace and blessings be upon him) had gone into prostration.
Al-Bazzar recorded it; its chain contains al-Mufaddal bin Sadaqah, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2410