Ambrosiaster — on Rom 8:26 (COMMENTARY ON PAUL'S EPISTLES)

“Our prayers are weak because they ask for things contrary to reason, and for this reason Paul shows that this weakness in us is helped by the Holy Spirit who has been given to us. The Holy Spirit helps because he does not allow anything we ask for before the proper time or against God's wishes to happen.Paul says that the Spirit intercedes for us not with human words but according to his own nature. For when what comes from God speaks with God, it is obvious that he will speak in the same way as the one from whom he comes speaks. For the Spirit given to us overflows with our prayers in order to make up for our inadequacy and lack of foresight by his actions and to ask God for the things which will be of benefit to us.”