Hebrews 12:11

Now for the time being no discipline seems to be pleasant; it is painful; later on, however, to those who are trained by it, it yields the fruit of peace which grows from upright character.

Matthew 10:37

Anybody who loves father or mother more than he loves me is not worthy of me,

Treasury of Scripture Knowledge

Summary

And the thing was very grievous in Abraham's sight because of his son.

Bible References

Because

Matthew 10:37
Anybody who loves father or mother more than he loves me is not worthy of me,
Hebrews 12:11
Now for the time being no discipline seems to be pleasant; it is painful; later on, however, to those who are trained by it, it yields the fruit of peace which grows from upright character.