Luke 24:16

Eyes were holden. They were weary and so absorbed with their own gloomy thoughts that they did not observe Jesus closely as He joined them. Similar circumstances had apparently prevented Mary from recognizing Jesus at first, earlier the same day. In some of the postresurrection appearances Jesus was instantly recognized, or so it seems, while in others He was not. The words of Luke, here and in v. 31, imply in this case a supernatural dimming of the senses of the two disciples in addition to their self-preoccupation.

Should not know. Jesus might have revealed Himself immediately, but had He done so they might have been so elated as not to appreciate fully or to remember well the important truths He was about to impart to them. It was essential for them to understand the Messianic prophecies of the OT, together with the historical incidents and sacred rites that pointed forward to Christ. These alone could provide a firm foundation for their faith. A supposed faith in Christ that is not firmly rooted in the teachings of the Scriptures cannot possibly remain steadfast when the storms of doubt blow (see on Matt. 7:24-27).

It was the fulfillment of the OT in the events recorded later in the NT to which Jesus now drew their attention (see DA 799).