I do set my {k} bow in the cloud, and it shall be for a token of a covenant between me and the earth.

(k) By this we see that signs or ordinances should not be separate from the word.

Wesley's Notes

9:13 I set my bow in the clouds - The rainbow, 'tis likely was seen in the clouds before, but was never a seal of the covenant 'till now. Now, concerning this seal of the covenant, observe, This seal is affixed with repeated assurances of the truth of that promise, which it was designed to be the ratification of; I do set my bow in the cloud, Ge 9:13. It shall be seen in the cloud, Ge 9:14. and it shall be a token of the covenant, Ge 9:12,13. And I will remember my covenant, that the waters shall no more become a flood, Ge 9:15. Nay, as if the eternal Mind needed a memorandum, I will look upon it that I may remember the everlasting covenant, Ge 9:16. The rainbow appears when the clouds are most disposed to wet; when we have most reason to fear the rain prevailing, God shews this seal of the promise that it shall not prevail. The rainbow appears when one part of the sky is clear, which imitates mercy remembered in the midst of wrath, and the clouds are hemmed as it were with the rainbow, that it may not overspread the heavens, for the bow is coloured rain, or the edges of a cloud gilded. As God looks upon the bow that he may remember the covenant, so should we, that we also may be ever mindful of the covenant with faith and thankfulness.

Scofield Reference Notes

Margin bow

The bow is not said to have come into existence at this time, but only to have been here invested with the character of a sign, CF. Ex 31:13. Typically, the bow, seen upon the storm clouds of judgment Gen 7:11 has been thought to speak of the cross where judgment, never to be repeated has been visted upon the believer's sins. Gal 3:10-14 Heb 10:14-18.

Jamieson-Fausset-Brown Bible Commentary

13. I do set my bow in the cloud-set, that is, constitute or appoint. This common and familiar phenomenon being made the pledge of peace, its appearance when showers began to fall would be welcomed with the liveliest feelings of joy.

Matthew Henry's Concise Commentary

9:8-17 As the old world was ruined, to be a monument of justice, so this world remains to this day a monument of mercy. But sin, that drowned the old world, will burn this. Articles of agreement among men are sealed, that what is promised may be the more solemn, and the doing of what is covenanted the more sure to mutual satisfaction. The seal of this covenant was the rainbow, which, it is likely, was seen in the clouds before, but was never a seal of the covenant till now it was made so. The rainbow appears when we have most reason to fear the rain prevailing; God then shows this seal of the promise, that it shall not prevail. The thicker the cloud, the brighter the bow in the cloud. Thus, as threatening afflictions abound, encouraging consolations much more abound. The rainbow is the reflection of the beams of the sun shining upon or through the drops of rain: all the glory of the seals of the covenant are derived from Christ, the Sun of righteousness. And he will shed a glory on the tears of his saints. A bow speaks terror, but this has neither string nor arrow; and a bow alone will do little hurt. It is a bow, but it is directed upward, not toward the earth; for the seals of the covenant were intended to comfort, not to terrify. As God looks upon the bow, that he may remember the covenant, so should we, that we may be mindful of the covenant with faith and thankfulness. Without revelation this gracious assurance could not be known; and without faith it can be of no use to us; and thus it is as to the still greater dangers to which all are exposed, and as to the new covenant with its blessings.