Go quickly now. There's a clear picture of what Simeon and Anna intimately knew. It is found right there in Luke 2: 25 - 38.
The grass withers, the flower fades; but the word of our God will stand forever. Isaiah 40:8
So shall my word be that goes out from my mouth; it shall not return to me empty, but it shall accomplish that which I purpose, and succeed in the thing for which I sent it.
Isaiah 55:11