Luke 9:62
Jesus said to him, "No one is any use to the Reign of God who puts his hand to the plough and then looks behind him."
Acts 15:37-38
But while Barnabas wanted to take John (who was called Mark) along with them,
Philippians 3:13
Brothers, I for one do not consider myself to have appropriated this; my one thought is, by forgetting what lies behind me and straining to what lies before me,
Hebrews 10:38
Meantime my just man shall live on by his faith; if he shrinks back, my soul takes no delight in him.
Luke 17:31-32
On that day, if a man is on the housetop and his goods inside the house, he must not go down to fetch them out; nor must a man in the field turn back
2 Timothy 4:10
for Demas, in his love for this world, has deserted me and gone to Thessalonica; Crescens is off to Gaul, Titus to Dalmatia,
James 1:6-8
Only, let him ask in faith, with never a doubt; for the doubtful man is like surge of the sea whirled and swayed by the wind;
2 Peter 2:20-22
After escaping the pollutions of the world by the knowledge of our Lord and saviour Jesus Christ, if they get entangled and overpowered again, the last state is worse for them than the first.