Christian critics treated God blessing Muhammad as God praying due to wordplay

Evidence

The idea of God’s praying derives from the Arabic use in this context (‘God’s blessing upon Muhammad’ or ‘may God bless him’) of the same word as is used for the ritual worship or prayer: in the Qur’anic verse cited by Ricoldo it is ‘yusaliina’, God and the angels bless Muhammad. — Norman Daniel, Islam and the West, 1989