Hebrews 12:11

Indeed no chastisement for the present seems to be truly joyful, but sorrowful: but afterward it yields the peaceable fruit of righteousness to them who have been disciplined by it.

Matthew 10:37

He that loveth father and mother more than me is not worthy of me; and he that loveth son or daughter more than 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
He that loveth father and mother more than me is not worthy of me; and he that loveth son or daughter more than me is not worthy of me.
Hebrews 12:11
Indeed no chastisement for the present seems to be truly joyful, but sorrowful: but afterward it yields the peaceable fruit of righteousness to them who have been disciplined by it.