Adam Clarke on Matthew 18:10

One of these little ones - One of my simple, loving, humble disciples.

Their angels - always behold - Our Lord here not only alludes to, but, in my opinion, establishes the notion received by almost all nations, viz. That every person has a guardian angel; and that these have always access to God, to receive orders relative to the management of their charge. See Psa 34:8; Heb 1:14.

Always behold the face - Hence, among the Jews, the angels were styled מלכי פנים, malakey panim, angels of the face, and Michael is said to be סר הפנים, sar ha-panim the prince of the face. This is an allusion to the privilege granted by eastern monarchs to their chief favourites; a privilege which others were never permitted to enjoy. The seven princes of Media and Persia, who were the chief favourites and privy-counsellors of Ahasuerus, are said to see the king's face. Est 1:14; see also 2Kgs 25:19, and Jer 51:25. Our Lord's words give us to understand that humble-hearted, child-like disciples, are objects of his peculiar care, and constant attention. The clause, εν ουρανοις, in the heavens, is wanting in several MSS., versions, and fathers.