All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
Saying such a statement is not Shirk. What you mentioned, that no one except Allah, the Exalted, can give reward, does not necessitate that this statement is Shirk. The general indication of the statement is open for interpretation, since it is permissible for the Muslim – according to many scholars – to dedicate the reward of his good deeds to others. For more benefit, please refer to fatwa 276133.
Allah knows best.