This reading is from the special Torah portion read on the Shabbat during festival of Sukkot.
You shall observe the Feast of Weeks, of the first fruits of the wheat harvest; and the Feast of Ingathering at the turn of the year. Three times a year all your males shall appear before the Sovereign Lord, the God of Israel. I will drive out nations from your path and enlarge your territory; no one will covet your land when you go up to appear before the Lord your God three times a year.
You shall not offer the blood of My sacrifice with anything leavened; and the sacrifice of the Feast of Passover shall not be left lying until morning. The choice first fruits of your soil you shall bring to the house of the Lord your God. You shall not boil a kid in its mother's milk.