AHMAD 5914:
from Ibn ʿUmar —
[Machine] The Messenger of Allah ﷺ said: "Whoever says to his brother, 'O disbeliever,' one of them has indeed earned it."
أحمد ٥٩١٤:
عن ابن عمر —
قَالَ رَسُولُ اللهِ ﷺ مَنْ قَالَ لِأَخِيهِ يَا كَافِرُ فَقَدْ بَاءَ بِهَا أَحَدُهُمَا