This Bible contradiction is from the Skeptic's Annotated Bible.
For six days
Deuteronomy 16:8 View context
Six days thou shalt eat unleavened bread: and on the seventh day [shall be] a solemn assembly to the LORD thy God: thou shalt do no work [therein].
For seven days
Deuteronomy 16:3 View context
Thou shalt eat no leavened bread with it; seven days shalt thou eat unleavened bread therewith, [even] the bread of affliction; for thou camest forth out of the land of Egypt in haste: that thou mayest remember the day when thou camest forth out of the land of Egypt all the days of thy life.
Exodus 12:15 View context
Seven days shall ye eat unleavened bread; even the first day ye shall put away leaven out of your houses: for whosoever eateth leavened bread from the first day until the seventh day, that soul shall be cut off from Israel.
Exodus 23:15 View context
Thou shalt keep the feast of unleavened bread: (thou shalt eat unleavened bread seven days, as I commanded thee, in the time appointed of the month Abib; for in it thou camest out from Egypt: and none shall appear before me empty:)