Exodus 12:20-22

Young's Literal Translation

²⁰ anything fermented ye do not eat, in all your dwellings ye do eat unleavened things.'

²¹ And Moses calleth for all the elders of Israel, and saith unto them, `Draw out and take for yourselves [from] the flock, for your families, and slaughter the passover-sacrifice;

²² and ye have taken a bunch of hyssop, and have dipped [it] in the blood which [is] in the basin, and have struck [it] on the lintel, and on the two side-posts, from the blood which [is] in the basin, and ye, ye go not out each from the opening of his house till morning.