The law does promise to give on condition that we fulfill it's demands

"In the law as a covenant of works there is also a promise, a gracious promise of the continuance of spiritual and temporal life and, in due time, of eternal life. This promise, which flowed solely from infinite benignity and condescension in God, was made, and was to have been fulfilled, to Adam and all his natural posterity, on condition that he as their representative perfectly obeyed the precept." - John Colquhoun, A treatise on the law and gospel, pg. 15 this is on the law in general.