It is narrated from Ali bin Husayn bin Ali bin Abi Talib (may Allah have mercy on him) that whenever the Messenger of Allah (peace and blessings be upon him) went down or rose up, he would say the takbir. This remained his (peace and blessings be upon him) prayer until he (peace and blessings be upon him) passed on to Allah.
It is a good (hasan) mursal report.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2493