The infirmities in Romans 8:26-27 have to do with certain weaknesses in our prayer life.
Likewise, the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered. And he that searcheth the hearts knoweth what is the mind of the Spirit, because he maketh intercession for the saints according to the will of God. Romans 8:26, 27 King James Version
The Holy Spirit, Paul says, helps them. The Greek word translated “helpeth,” literally means “to lend a hand together with, and at the same time with one.” Martha used the same word when appealing to our Lord to bid Mary help her with the preparation of the meal (Luke 10:40). The Holy Spirit lends a hand together with us as we are praying. It is not that He helps us bear our weaknesses, but He helps our weaknesses.
The weaknesses spoken of here are two, what we should pray for, the matter of prayer, and how we should pray, the form and manner of our prayer. The word “what” has an article before it in the Greek. Literally, we do not know “the what” to pray for. That is, we do not know the particular definite thing to pray for. As to the general subjects for prayer, the salvation of the lost, the sanctification of the saints, our daily needs, these we know of. But to be specific in our praying involves a knowledge of God’s will in particular instances, and of that we are naturally ignorant. It is right here that the Spirit comes to our aid.
The word “pray” is from a Greek word made up of a word which means “to pray,” with a prefixed preposition which means literally “toward.” The composite word refers to prayer directed to God, a conscious definite commitment to Him of our needs, our desires, our petitions. The Holy Spirit thus energizes the saint along the line of prayer for particular things which are according to the will of God, prayer directed consciously to Him.
The word translated “know,” is not the Greek word which means “knowledge gained by experience,” but “knowledge that is intuitive, natural to one’s being and constitution.” We do not have intuitive knowledge of the particular thing to pray for. The word “ought” is the same word used in John 3:7 in the word “must.” Literally, it means, “it is necessary in the nature of the case.” The necessity in the nature of the case is found in the fact that God brings His plans to fruition through the prayers of the saints, and in order for us to pray according to the will of God, we must be so yielded to the control of the Spirit that He can bring into our prayer ministry, the things which God is planning to accomplish. It is clear, therefore, that in order to pray aright, we must be filled with the Spirit.
The Spirit Himself, not “itself,” should be the translation here. The word “spirit” in the Greek language is in the neuter gender, and consequently, its pronoun is neuter. But the Holy Spirit is a Person, and should not be referred to as “it.” The translation should be according to sense here, not grammar.
He makes intercession. This word comes from a Greek word which is most picturesque. It is used of one who happens upon one who is in trouble and pleads in that one’s behalf. As Alford says, “The Holy Spirit of God dwelling in us, knowing our wants better than we, Himself pleads in our prayers, raising us to higher and holier desires than we can express in words, which can only find utterance in sighings and aspirations.”
God the Father who searches the hearts of His saints for their prayers, uttered and unexpressed, interprets those inarticulate sighings of the Spirit in us by reason of the fact that the Spirit pleads for us and in us and through us according to the will of God.
The lesson for us here is that if we expect to have an intelligent, powerful, rich prayer life, we must live Spirit controlled lives.
Editor’s Addition: I believe the praying in the Spirit mentioned here refers to praying in tongues. More specifically, the intercession aspect of praying in tongues, where the Holy Spirit moves us into deep groanings. While praying in tongues you do not know exactly what the words or sounds mean. You must believe that you are praying the perfect prayer aligned with the perfect will of God. You can know this because it is the Holy Spirit praying through you.