Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that whenever he would bow or rise (in prayer), he would say «الله اكبر», and he would say: My prayer is the most similar to the prayer of the Messenger of Allah (peace and blessings be upon him) among all of you.
Hadith Referenceالمنتقى ابن الجارود / كتاب الصلاة / 191