That Constantine was displeased with one who praised him excessively
And now that all these ceremonies were completed, and the divine qualities of the emperor's character continued to be the theme of universal praise, one of God's ministers presumed so far as in his own presence to pronounce him blessed, as having been counted worthy to hold absolute and universal empire in this life, and as being destined to share the empire of the Son of God in the world to come. These words, however, Constantine heard with indignation, and forbade the speaker to hold such language, exhorting him rather to pray earnestly on his behalf, that whether in this life or in that which is to come, he might be found worthy to be a servant of God.
Source: Life of Constantine (New Advent)