'Festival' in the Bible

These things I [vividly] remember as I pour out my soul;How I used to go along before the great crowd of people and lead them in procession to the house of God [like a choirmaster before his singers, timing the steps to the music and the chant of the song],With the voice of joy and thanksgiving, a great crowd keeping a festival.

The Lord is God, and He has given us light [illuminating us with His grace and freedom and joy].Bind the festival sacrifices with cords to the horns of the altar.