John Calvin, Commentary on Mattthew, Mark and Luke (Vol.1), Mat. 8:19-22

Whence arose the great readiness of the scribe to prepare himself immediately to accompany Christ, but from his not having at all considered the hard and wretched condition of his followers? We must bear in mind that he was a scribe, who had been accustomed to a quiet and easy life, had enjoyed honor, and was ill-fitted to endure reproaches, poverty, persecutions, and the cross. He wishes indeed to follow Christ, but dreams of an easy and agreeable life, and of dwellings filled with every convenience; whereas the disciples of Christ must walk among thorns, and march to the cross amidst uninterrupted afflictions. The more eager he is, the less he is prepared. He seems as if he wished to fight in the shade and at ease, neither annoyed by sweat nor by dust, and beyond the reach of the weapons of war. There is no reason to wonder that Christ rejects such persons: for, as they rush on without consideration, they are distressed by the first uneasiness of any kind that occurs, lose courage at the first attack, give way, and basely desert their post. Besides, this scribe might have sought a place in the family of Christ, in order to live at his table without expense, and to feed luxuriously without toil. Let us therefore look upon ourselves as warned, in his person, not to boast lightly and at ease, that we will be the disciples of Christ, while we are taking no thought of the cross, or of afflictions; but, on the contrary, to consider early what sort of condition awaits us. The first lesson which he gives us, on entering his school, is to deny ourselves, and take up his cross, (Matthew 16:24.)