Numbers 6:20

קדש הוא לכהן IT IS HOLY FOR THE PRIEST — The cake, the wafer and the shoulder are a heave-offering for the priest. על חזה התנופה means: BESIDES THE BREAST AND THE SHOULDER which are due to him (the priest) from all feast-offerings, there is to be added to the portions assigned to the priest in the case of the Nazarite’s feast-offerings, this shoulder. Because the feast-offerings of the Nazarite are included in the general rule governing feast-offerings but were excepted to become subject to a new matter — the setting apart of the shoulder for the priest — it became necessary to restore them to the general rule of שלמים by expressly stating that they are subjected also to the setting apart of the breast and thigh as are שלמים in general (Sifrei Bamidbar 37).

וְהֵנִיף֩ אוֹתָ֨ם הַכֹּהֵ֥ן ׀ תְּנוּפָה֮ לִפְנֵ֣י יְהֹוָה֒ קֹ֤דֶשׁ הוּא֙ לַכֹּהֵ֔ן עַ֚ל חֲזֵ֣ה הַתְּנוּפָ֔ה וְעַ֖ל שׁ֣וֹק הַתְּרוּמָ֑ה וְאַחַ֛ר יִשְׁתֶּ֥ה הַנָּזִ֖יר יָֽיִן׃

and the priest shall wave them for a wave offering before the Lord: this is holy for the priest, with the wave breast and heave shoulder: and after that the Nazir may drink wine.