Romans 8:26-27 (NRSV)
26 Likewise the Spirit helps us in our weakness; for we do not know how to pray as we ought, but that very Spirit intercedes with sighs too deep for words. 27 And God, who searches the heart, knows what is the mind of the Spirit, because the Spirit intercedes for the saints according to the will of God.
1 Corinthians 2:10-16 (NASB77)
10 For to us God revealed them through the Spirit; for the Spirit searches all things, even the depths of God. 11 For who among men knows the thoughts of a man except the spirit of the man, which is in him? Even so the thoughts of God no one knows except the Spirit of God. 12 Now we have received, not the spirit of the world, but the Spirit who is from God, that we might know the things freely given to us by God, 13 which things we also speak, not in words taught by human wisdom, but in those taught by the Spirit, combining spiritual thoughts with spiritual words. 14 But a natural man does not accept the things of the Spirit of God; for they are foolishness to him, and he cannot understand them, because they are spiritually appraised. 15 But he who is spiritual appraises all things, yet he himself is appraised by no man. 16 For WHO HAS KNOWN THE MIND OF THE LORD, THAT HE SHOULD INSTRUCT HIM? But we have the mind of Christ.