Midrash for Menachot 130:2

כתוב אחד אומר (ויקרא כג, טז) תספרו חמשים יום וכתוב אחד אומר (ויקרא כג, טו) שבע שבתות תמימות תהיינה

R. Ishmael says. The Torah says. Bring the 'Omer-offering on the Passover, and the Two Loaves on the Feast of Weeks. Just as the latter are offered on the Festival, and indeed at the beginning of the Festival, so the former, too. Is offered on the Festival, and indeed at the beginning of the Festival. R. Judah b. Bathyra says. There is written 'Sabbath' below and also 'Sabbath' above; just as in the former case the Festival, and indeed the beginning of the Festival, is near [to the Sabbath]. so in the latter case, too, the Festival, and indeed the beginning of the Festival, is near [to the 'Omer]. <br>

Sifrei Devarim