Charles Ellicott Commentary Romans 8:26

"And in like manner the Spirit also helpeth our infirmity: for we know not how to pray as we ought; but the Spirit himself maketh intercession for [us] with groanings which cannot be uttered;" — Romans 8:26 (ASV)

Likewise.—While on the one hand the prospect of salvation sustains him, on the other hand, the Divine Spirit intervenes to aid him. The one source of encouragement is human (his own human consciousness of the certainty of salvation); the other is divine.

Infirmities.—The correct reading is the singular, “infirmity.” Without this assistance, we might be too weak to endure, but the Spirit helps and strengthens our weakness by inspiring our prayers.

With groanings which cannot be uttered.—When the Christian’s prayers are too deep and too intense for words, when they are rather a sigh heaved from the heart than any formal utterance, then we may know that they are prompted by the Spirit Himself. It is He who is praying to God for us.

On Romans 8:26-27:

A second reason for the patience of the Christian under suffering. The Spirit helps his weakness and joins in his prayers.