Thy Word was written by Amy Grant and Michael W. Smith for the Album Straight Ahead. It’s chorus is taken from Psalm 119:105 (KJV).
Songfacts tells us about how this song was written.
Michael originally came up with the song’s melody and some words for the chorus straight from David’s Psalms about being a light into my path. Amy fell in love with his demo, but as Michael had no idea what the verses were supposed to say, he gave it to her and told her she could finish the tune. “So later that night she starts walking back to her cabin,” Michael told us. “And you have to understand Caribou Ranch is an 8,000 acre ranch and it’s very dark, and you’re in the middle of nowhere. And she got lost. There’s bears and all that sort of thing. You’ve got to really know where you’re going. It’s obviously a compound with all these cabins and stuff.”
“She finally saw a lamp and started walking towards that light, didn’t realize that that was her cabin,” he continued. “And she walked into that little cabin and sat down with a notebook and pen and wrote the verses to ‘Thy Word.'”
Here is another video of Thy Word: