The first occurrence.
And God saw the light, that it was good: and God divided the light from the darkness. Gen 1:4
The primitive root.
Strong’s H914 בדל badal, a primitive root meaning, “to separate.” The 3-letter root is bet + dalet + lamed.
bet ב = the house, thus house, household, family, in, within
dalet ד = the door, thus enter, move, hang
lamed ל = the shepherd’s staff, thus teach, yoke, to, bind
The story: At the tent (bet) door (dalet), the patriarch (lamed) sits to render judgment, i.e., to separate truth from lies, and the good course from the evil course.
All judgments and binding contractual business in the patriarchal era was conducted either at the door of the tribal authority, who was the patriarch of the tribe, where he sat in the shade to decide family matters:
Then YHVH appeared to him by the terebinth trees of Mamre, as he was sitting in the tent door in the heat of the day. So he lifted his eyes and looked, and behold, three men were standing by him; and when he saw them, he ran from the tent door to meet them, and bowed himself to the ground. Gen 18:1-2
Or at the gate of the city, where the elders congregated:
Then Abraham stood up and bowed himself to the people of the land, the sons of Heth. And he spoke with them, saying, “If it is your wish that I bury my dead out of my sight, hear me, and meet with Ephron the son of Zohar for me, that he may give me the cave of Machpelah which he has, which is at the end of his field. Let him give it to me at the full price, as property for a burial place among you.” Now Ephron dwelt among the sons of Heth; and Ephron the Hittite answered Abraham in the presence of the sons of Heth, all who entered at the gate of his city, saying, … Gen 23:7-10