Imam Ali (as) said “The worst sin is that which the one who commits it takes it lightly.”[i]
[i] Nahjul Balagha saying #486
Prophet Solomon (as) told his son “Beware of being argumentative for there is no benefit in it. It only serves to foment enmity among brethren.”
God’s Emissaries: Adam to Jesus by Sheikh Arastu
Bihar al-Anwar Vol. 14 Pg 134 H.9