The Apostle Paul alludes to the practice of "praying in the Spirit" in at least two of his epistles, namely:
Ephesians 6:18 (ESV):
18 praying at all times in the Spirit, with all prayer and supplication. To that end, keep alert with all perseverance, making supplication for all the saints,
1 Corinthians 14:13-1516 (ESV):
13 Therefore, one who speaks in a tongue should pray that he may interpret. 14 For if I pray in a tongue, my spirit prays but my mind is unfruitful. 15 What am I to do? I will pray with my spirit, but I will pray with my mind also; I will sing praise with my spirit, but I will sing with my mind also. 16 Otherwise, if you give thanks with your spirit, how can anyone in the position of an outsider say “Amen” to your thanksgiving when he does not know what you are saying?
Unfortunately, Paul didn't provide a crystal clear definition of the practice.
Jude also alludes to this type of prayer, but he doesn't explain what it means either:
20 But you, beloved, building yourselves up in your most holy faith and praying in the Holy Spirit, 21 keep yourselves in the love of God, waiting for the mercy of our Lord Jesus Christ that leads to eternal life. [Jude 1:20-21, ESV]
How did the early Church in the ante-Nicene period understand the practice of "praying in the Spirit"? Was it understood as a special kind of prayer, differentas distinct from the "normalmore "basic" mode of prayer"prayer? Are there any extra-biblical writings from the ante-Nicene period addressing this topic?
Related BH.SE question: Are “praying in a tongue”, “praying with one's spirit” and “praying in the (Holy) Spirit” interchangeable expressions?