Authentic Supplication Number 91.

The Messenger of Allah  used to say Sami`al-lahu liman hamidahu (106) while lifting his spine from the bow, then he would say in the upright position: Rabbana walakal-hamdu (107), and in one narration: Rabbana lakal-hamdu (108).

(106) Allah hears the one that praises Him.
(107) Our Lord, and to You is all praise.
(108) Our Lord: to You is all praise.

Ibn Taymiya said that Rabbana lakal-hamdu is a sound expression. He said that the coinciding expressions that are in both [Saheeh ‘Al-Bukhari and Saheeh Muslim are: Rabbana wa lakal-hamdu, and Allahumma rabbana lakal hamdu. Al-Albani included this hadeeth in The Authentic of Good Sayings as #74.