Along with his peace offering of thanksgiving he is to present an offering with cakes of leavened bread.

Leviticus 2:12
You may bring them to the LORD as an offering of firstfruits, but they are not to be offered on the altar as a pleasing aroma.

Leviticus 23:17
Bring two loaves of bread from your dwellings as a wave offering, each made from two-tenths of an ephah of fine flour, baked with leaven, as the firstfruits to the LORD.

Leviticus 23:18
Along with the bread you are to present seven unblemished male lambs a year old, one young bull, and two rams. They will be a burnt offering to the LORD, together with their grain offerings and drink offerings--an offering made by fire, a pleasing aroma to the LORD.

Jeremiah 33:11
the sounds of joy and gladness, the voices of the bride and bridegroom, and the voices of those bringing thank offerings into the house of the LORD, saying: 'Give thanks to the LORD of Hosts, for the LORD is good; His loving devotion endures forever.' For I will restore the land from captivity as in former times, says the LORD.

Amos 4:5
Offer leavened bread as a thank offering, and loudly proclaim your freewill offerings. For that is what you children of Israel love to do," declares the Lord GOD.

Besides the cakes, he shall offer for his offering leavened bread with the sacrifice of thanksgiving of his peace offerings.