tn The expression “the sweat of your brow” is a metonymy, the sweat being the result of painful toil in the fields.
snUntil you return to the ground. The theme of humankind’s mortality is critical here in view of the temptation to be like God. Man will labor painfully to provide food, obviously not enjoying the bounty that creation promised. In place of the abundance of the orchard’s fruit trees, thorns and thistles will grow. Man will have to work the soil so that it will produce the grain to make bread. This will continue until he returns to the soil from which he was taken (recalling the creation in 2:7 with the wordplay on Adam and ground). In spite of the dreams of immortality and divinity, man is but dust (2:7), and will return to dust. So much for his pride.
sn In general, the themes of the curse oracles are important in the NT teaching that Jesus became the cursed one hanging on the tree. In his suffering and death, all the motifs are drawn together: the tree, the sweat, the thorns, and the dust of death (see Ps 22:15). Jesus experienced it all, to have victory over it through the resurrection.