Deuteronomy 16:1, 10, 13
Deuteronomy 16:1 NIV
Observe the month of Aviv and celebrate the Passover of the LORD your God, because in the month of Aviv he brought you out of Egypt by night.
Deuteronomy 16:10 NIV
Then celebrate the Festival of Weeks to the LORD your God by giving a freewill offering in proportion to the blessings the LORD your God has given you.
Deuteronomy 16:13 NIV
Celebrate the Festival of Tabernacles for seven days after you have gathered the produce of your threshing floor and your winepress.