Matthew 7:14

7:14 But the gate is narrow and the way is difficult that leads to life, and there are few who find it.

Luke 13:24

13:24 “Exert every effort ¹  to enter through the narrow door, because many, I tell you, will try to enter and will not be able to.

¹ tn Or “Make every effort” (L&N 68.74; cf. NIV); “Do your best” (TEV); “Work hard” (NLT); Grk “Struggle.” The idea is to exert one’s maximum effort (cf. BDAG 17 s.v. ἀγωνίζομαι 2.b, “strain every nerve to enter”) because of the supreme importance of attaining entry into the kingdom of God.