Num 9:11

בַּחֹ֨דֶשׁ הַשֵּׁנִ֜י בְּאַרְבָּעָ֨ה עָשָׂ֥ר י֛וֹם בֵּ֥ין הָעַרְבַּ֖יִם יַעֲשׂ֣וּ אֹת֑וֹ עַל־מַצּ֥וֹת וּמְרֹרִ֖ים יֹאכְלֻֽהוּ׃

Such people are to observe it at twilight on the fourteenth day of the second month. They are to eat the lamb, together with unleavened bread and bitter herbs;