Ephesians 6:18 AMPC

18 Pray at all times (on every occasion, in every season) in the Spirit, with all [manner of] prayer and entreaty. To that end keep alert and watch with strong purpose and perseverance, interceding in behalf of all the saints (God's consecrated people).

Romans 8:26-27 KJV

26 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.
27 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.

Luke 18:1 KJV

1 And he spake a parable unto them to this end, that men ought always to pray, and not to faint;