Albert Barnes Commentary Ecclesiastes 11:3-6

"If the clouds be full of rain, they empty themselves upon the earth; and if a tree fall toward the south, or toward the north, in the place where the tree falleth, there shall it be. He that observeth the wind shall not sow; and he that regardeth the clouds shall not reap. As thou knowest not what is the way of the wind, [nor] how the bones [do grow] in the womb of her that is with child; even so thou knowest not the work of God who doeth all. In the morning sow thy seed, and in the evening withhold not thy hand; for thou knowest not which shall prosper, whether this or that, or whether they both shall be alike good." — Ecclesiastes 11:3-6 (ASV)

“Unforeseen events come from God; and the man who is always gazing on the uncertain future will neither begin nor complete any useful work: but bear in mind that times and circumstances, the powers of nature, and the results they produce, are in the hand of God; and be both diligent and trustful.”

The images are connected chiefly with the occupation of an agricultural laborer: the discharge of rain from the cloud, the inclination of the falling tree, and the direction of the wind, are beyond his control, though the result of his work is affected by them.

The common application of the image of the fallen tree to the state of departed souls was probably not in the mind of the inspired writer (Ecclesiastes 11:5).

Spirit - The same Hebrew word (like πνεῦμα pneuma in Greek and “Spirit” in English) signifies both the wind (Ecclesiastes 11:4) and the Spirit (compare the marginal reference). The Old Testament in many places recognizes the special operation of God (Job 10:8–12; Psalms 139:13–16; Jeremiah 1:5), and distinctly of the Spirit of God (Job 31:15) in the origination of every child. Compare (Genesis 2:7).