Anyone who says to a brother or sister, 'RACA,’ is answerable to the court

[TonyChanYT]

Berean Standard Bible, Matthew 5:

I tell you that anyone who is angry with his brother will be subject to judgment. Again, anyone who says to his brother, ‘Raca,’ will be subject to the Sanhedrin. But anyone who says, ‘You fool!’ will be subject to the fire of hell.

Strong's Greek: 4469. ῥακά (rhaka) — 1 Occurrence

BDGA:

a term of abuse/put-down relating to lack of intelligence, numskull, fool … empty-head. … [It] is not an expression denoting a strong put-down. .. It is a colloquial term of rather gentle cheek and generally used in familiar surroundings.

Expositor's Greek Testament:

Raca expresses contempt for a man’s head = you stupid!

"Raca" was a mild insult. Jesus warned us against insulting our brothers in the Sermon on the Mount.