Matthew 18:10 “Take heed that ye despise not one of these little ones; for I say unto you, That in heaven their angels do always behold the face of my Father which is in heaven.”

John Wesley Commentary comments on this verse:  See that ye despise not one of these little ones – As if they were beneath your notice.  Be careful to receive and not to offend, the very weakest believer in Christ: for as inconsiderable as some of these may appear to thee, the very angels of God have a peculiar charge over them: even those of the highest order, who continually appear at the throne of the Most High.”

Barnes NT Commentary says:  “Take heed that ye despise not one of these little ones,” etc. That is, one who has become like little children – or, a Christian. Jesus then proceeds to state the reason why we should not despise his feeblest and obscurest follower. That reason is drawn from the care which God exercises over them. The first instance of that care is, that in heaven their angels do always behold his face. He does not mean, I suppose, to state that every good man has his guardian angel, as many of the Jews believed; but that the angels were, in general, the guards of his followers, and aided them, and watched over them (Heb 1:14). 
 
“Do always behold the face of my Father,” etc. This is taken from the practice of earthly courts. To be admitted to the presence of a king; to be permitted to see his face continually; to have free access at all times, was deemed a mark of peculiar favour, (1Kings 10:8; Es 1:14) and was esteemed a security for his protection. So, says our Saviour, we should not despise the obscurest Christians, for they are ministered to by the highest and noblest of beings; beings who are always enjoying the favour and friendship of God.

C.H. Spurgeon’s Commentary on Matthew says:  Those who are servants to poor saints and little children are allowed free entrance to the King: what must he think of his little ones themselves? Nay, this is not all. Jesus himself cares for the poorest and neediest. Yes, he came to save that which was lost. How dare we then be proud, and despise a child because of its youth, or a man because of his poverty, or his want of intelligence? The angels and the angels’ Lord care for the most despised of our race; shall not we?