And the men of Ephraim gathered themselves together, and went northward, and said unto Jephthah, Wherefore passedst thou over to fight against the children of Ammon, and didst not call us to go with thee? we will burn thine house upon thee with fire. (Judges 12:1)
Hebrew, ṣaphonah. Gilead was to the east and northeast of Ephraim. Because of this, most Bible translations give the word as a proper name. There was a town by the name of Zaphon in the Jordan valley, on the Gilead side, not far from Succoth (Joshua 13:27).
Didst not call us.
Both here and in Judges 8:1-3 the tribe of Ephraim is presented in an unfavorable light. They were passive in time of oppression, and arrogant when others had taken the initiative and won the victory. Gideon had been conciliatory toward them and overlooked their boorishness, but Jephthah was in no mood to become subservient to them. Their alleged grievance stemmed from their desire to be regarded as the leading Israelite tribe. Their pride led them to resent having had no part in the glory of the victory. Moreover, they denied to Gilead the right of separate action, let alone that of choosing a ruler.
Passedst thou over.
They do not mean that he crossed the Jordan, but that he marched against the Ammonites.