This phrase implies that there were other flocks besides his own that were sheltered there. Perhaps two or three flocks were housed in a single enclosure. Only the sheep belonging to the shepherd would respond to his call. In Oriental lands today several flocks bivouac together at night, and in the morning each shepherd sets out in a different direction, calling out to his sheep.
Porter.
Literally, “doorkeeper.” The feminine form is translated “her that kept the door” (ch. 18:16). The “porter” had charge of the flock during the night. In the morning the shepherd would return, call his sheep by name, and lead them out to pasture.