Waiting and The Word
The group of 120 in Acts 1 are people who are following Jesus' instruction to wait for the promise of The Holy Spirit are devoting themselves to prayer. Perhaps being devoted to prayer is essential to be prepared to receive the great gift of The Holy Spirit. A prayerful person is a person who is seeking God.
There is also something else going on in this time of waiting that I see. These people are also people of God's word. Peter is recorded in Acts 1:15ff to have begun to talk to the group. He refers to the situation they are in as one that is a fulfillment of the scriptures.
More specifically Peter quotes 2 Psalms that "make sense" of the circumstances in which they have been engaged. Psalms 69:25 is quoted as referring to Judas and his betrayal of Jesus and the result. The scriptures are the way Peter helps these waiting to make sense of what has happened. He did not have the group look at the circumstances and try to make sense; Peter had the group look at the scriptures to make sense of it all. Then Peter quotes Psalm 109:8 to give scriptural evidence as to the need to replace Judas.
These people are not only people prayer but are also people of God's Word. Both prayer and scripture are necessary for the full living of life in Jesus. But it cannot be missed that even here there is still the need for the presence of The Holy Spirit. This is why Jesus told these people to wait, and that is what they are doing: waiting in prayer and waiting with scripture. This is not a bad plan if we still understand the need of The Holy Spirit!!
REFLECT: Is ,your and my life characterized by all of these: prayer, scripture, and The Holy Spirit?