Ikrimah said: I prayed with Sayyiduna Abu Hurayrah (may Allah be pleased with him), and he would say the takbir when rising and also when going down (into prostration). I mentioned this to Sayyiduna Ibn Abbas (may Allah be pleased with them both), and he said: "May you have no mother! Is that not the Sunnah of Abu al-Qasim (peace and blessings be upon him)?"
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11868