Matthew 13:21
hath not really root in himself, but is merely temporary: and when tribulation or persecution ariseth for the word's sake, immediately he is stumbled.
Luke 18:1
THEN he spake also to them a parable, to shew that we ought to pray always, and not faint;
Acts 10:2
a man of piety, and who feared God with all his house, giving much alms to the people, and praying to God continually.
Ephesians 6:18
praying at every opportunity with all prayer and supplication in Spirit, and watching for this very purpose with perseverance and intercession for all the saints;
1 Thessalonians 5:17
Pray without ceasing.