Charles Ellicott Commentary Genesis 8:10-12

"And he stayed yet other seven days; and again he sent forth the dove out of the ark; and the dove came in to him at eventide; and, lo, in her mouth an olive-leaf plucked off: so Noah knew that the waters were abated from off the earth. And he stayed yet other seven days, and sent forth the dove; and she returned not again unto him any more." — Genesis 8:10-12 (ASV)

Again he sent forth the dove ... — When, after another week’s delay, Noah again sent forth the dove, it remained away until “the time of evening,” finding both food and ground on which it could alight near the ark. It was not until nightfall that it came home, bringing to him an olive leaf pluckt off, or, possibly, a fresh olive-leaf. The olive-tree, which grows abundantly in Armenia, is said to vegetate under water; but what Noah wanted to learn was, not whether the topmost boughs were emerging from the flood, but whether the soil beneath was becoming free from water.

Now, after a seven days’ interval, when Noah again sent forth the dove, she did not return, “because the ground was dry.” It is therefore clear that the olive-tree had had plenty of time on some of the higher lands, while the flood was subsiding, to put forth new leaves. From this event the olive-leaf, thus sent by the regenerated earth to Noah in proof that she was ready to yield herself to him, has been ever since, among all mankind, the symbol of peace.