What is unique about the grain offering during the Feast of Weeks?
Leviticus 23:17 (ESV)
17You shall bring from your dwelling places two loaves of bread to be waved, made of two tenths of an ephah. They shall be of fine flour, and they shall be baked with leaven, as firstfruits to the LORD.
This is the only occasion when leaven is allowed to be brought as an offering to the Lord. It should be noted that the leavened bread is not taken to the altar; that is forbidden.
17 You shall bring from your dwelling places two loaves of bread to be waved, made of two tenths of an ephah. They shall be of fine flour, and they shall be baked with leaven, as firstfruits to the LORD.