Question: where in the bible does it say that saturday is the sabbath day?
Answer: No other day has ever been sanctified as the day of rest. The Sabbath Day begins at sundown on Friday and ends at sundown on Saturday. Genesis 2:1-3; Exodus 20:8-11; Isaiah 58:13-14; 56:1-8; Acts 17:2; Acts 18:4, 11; Luke 4:16; Mark 2:27-28; Matthew 12:10-12; Hebrews 4:1-11; Genesis 1:5, 13-14; Nehemiah 13:19.