Silsilah as-Sahihah 759 — When to say the transitional Takbirs

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that when the Noble Prophet (peace and blessings of Allah be upon him) intended to prostrate, he would say "Allahu Akbar," then he would prostrate, and when he intended to rise after sitting in the middle (Qa'dah), he would say "Allahu Akbar," then he would rise.