While it is the promise of God, receiving the Holy Spirit requires prayer and asking on our part. Luke 11:13 and John 4:10 clearly illustrate this point. The pouring out of the Holy Spirit is also contingent upon the obedience of the Lord’s instructions (Mt 28:20; Acts 5:32). Praying for the Holy Spirit does not deny the authority of God; instead, it is a natural expression of our faith (Mt 15:22-28; Rom 10:14), earnestness (Lk 11:5-8), and persistence (Lk 18:1-8).
The Lord Jesus told the disciples of the importance of receiving the Holy Spirit and specifically instructed them not to leave Jerusalem but to wait for the promise of the Holy Spirit (Lk 24:49; Acts 1:4-5, 8). The disciples themselves must have been eager to receive the Holy Spirit; that is why they prayed constantly. The only logical conclusion was that they were praying for the Holy Spirit.