The word "command" has a broader sense of meaning which includes the concept of "ordained" (i.e. "chosen"). It could also mean "appoint."

For example, the following verse uses the same Hebrew word "tsavah" (צָוָה) often translated as "command."

And it shall come to pass, when the LORD shall have done to my lord according to all the good that he hath spoken concerning thee, and shall have appointed ^H6680 thee ruler over Israel; (1 Samuel 25:30, KJV)

The widow may have known nothing of God's plan. But God knew she would feed Elijah--and that God would provide her the means to do so.

The word "command" has a broader sense of meaning which includes the concept of "ordained" (i.e. "chosen"). It could also mean "appoint."

For example, the following verse uses the same Hebrew word "tsavah" (צָוָה) often translated as "command."

And it shall come to pass, when the LORD shall have done to my lord according to all the good that he hath spoken concerning thee, and shall have appointed ^H6680 thee ruler over Israel; (1 Samuel 25:30, KJV)

The widow may have known nothing of God's plan. But God knew she would feed Elijah--and that God would provide her the means to do so.