1 Corinthians 14:2 [NKJV]
For he who speaks in a tongue does not speak to men but to God, for no one understands him; however, in the spirit he speaks mysteries.
When we pray in tongues, we speak mysteries in the Spirit. This weekend we have spent much time praying in the Spirit. It is never in vain. One day we shall reap the harvest of the time we have spent in prayer.
Romans 12:11-13 [NKJV]
11not lagging in diligence, fervent in spirit, serving the Lord; 12 rejoicing in hope, patient[c] in tribulation, continuing steadfastly in prayer; 13 distributing to the needs of the saints, given[d] to hospitality.