I ask myself where is the biblical instruction on this?
This is the Biblical principle:
Matt 10:34-36:
Do not think I came to bring peace to the earth; I came to bring, not peace, but a sword.+ 35 For I came to cause division, with a man against his father, and a daughter against her mother, and a daughter-in-law against her mother-in-law.+ 36 Indeed, a man’s enemies will be those of his own household. 37 Whoever has greater affection for father or mother than for me is not worthy of me; and whoever has greater affection for son or daughter than for me is not worthy of me.+