Albert Barnes' Notes on the Whole Bible - Matthew 28:16
Then the eleven disciples - Judas was dead, leaving but eleven of the original number of the apostles.Into a mountain where Jesus lead appointed them - This “appointment” is recorded in Matthew 26:32. On what particular mountain this was is not known. It is probable that Jesus, when he made the appointment, specified the place, which has been omitted by the evangelists. Matthew has omitted many appearances which Jesus made to his disciples which have been recorded by Luke, John, and Paul. See... read more
The Pulpit Commentary - Matthew 28:18-20
The commission. The angel at the sepulchre directed the women to announce the resurrection of Christ to his disciples and summon them to meet him in Galilee. Jesus himself afterwards appeared to them and repeated this instruction. The eleven accordingly repaired to the appointed place, and with them probably the five hundred brethren (see 1 Corinthians 15:6 ). "Some" of this number—some of those who had not seen him, like Thomas—"doubted" of the reality of the Resurrection, until they were... read more