Seeking him - Ζητουντες αυτον - or rather, seeking him diligently, αναζητουντες. This is the reading of BCDL, six others, Vulgate, and nine copies of the Itala. If they sought earnestly when they first found him missing, there is little doubt that their solicitude and diligence must be greatly increased during his three days' absence, therefore the word which I have adopted, on the above authority, is more likely to be the true reading than the ζητουντες of the common text, which simply signifies seeking; whereas the other strongly marks their solicitude and diligence.

And when they found him not,.... In the company that came from Jerusalem with them, nor among any of their relations and friends, with whom they supposed he was:
they turned back again to Jerusalem, that is, the next morning, for it can hardly be thought they would set out that night, after they had travelled all day, without taking some repose:
seeking him; at Jerusalem, in the streets and broad places of it; a figure of the church and ordinances, where souls look for, and inquire after their beloved, when they have lost him, Song 3:1.

After three sorrowing days, they find Him still in Jerusalem, not gazing on its architecture, or surveying its forms of busy life, but in the temple--not the "sanctuary" (as in Luke 1:9), to which only the priests had access, but in some one of the enclosures around it, where the rabbins, or "doctors," taught their scholars.