(a) After Jesus had ascended into heaven, the disciples. gathered together in one place as Jesus had commanded them. At this point, Peter stood among the brethren who were about 120 in number. He explained the need for the position of Judas Iscariot which had been left vacant to be filled. He made reference to the Bible i.e. the book of Psalm, which says " Let his habitation become desolate, and let there be no one to live in it; and his office let another take". Peter gave some conditions that must be fufilled by the would-be-appointee to the vacant post. The person must have witnessed and personally seen Jesus' works and heard his words and must have been a true witness to him. Two candidates were nominated for the post. They were Joseph Justus (also called Barnabas) and Mathias. They prayed for them. They cast lots for them and the lot fell on Mathias. He was numbered with the eleven disciples as a successor of Judas.

(b) Two lessons which we can learn from the incident are:
(i) The prayer, the casting of lots and the eventual election of Mathias show that God was behind the election.
(ii) God can always raise people to do his work.