Exodus 12:7

ולקחו מן הדם AND THEY SHALL TAKE OF THE BLOOD — This refers to the ritual reception of the blood. One might think that they must take it in the hand; therefore Scripture states, (v. 22) “[and ye shall dip it in the blood] which is in the basin (Mekhilta). המזוזת THE SIDE POSTS — These are the upright posts, one on this side of the entrance and one on that side. המשקוף THE LINTEL — This is the upper post upon which the door beats (שוקף) when it is being closed; old French lintel. The expression שקף (from which משקוף lintel is derived) denotes beating, as may be seen from the Targum on, (Leviticus 26:36) “the sound of a leaf that is beaten (by another)”, which Onkelos renders by דשקיף; and from the Targum on, (Exodus 21:25) חַבּוּרָה “wheal” (a beaten spot), where משקופי is the rendering. אל הבתים אשר יאכלו אתו בהם ON THE HOUSES WHEREIN THEY SHALL EAT IT — and not upon the lintel and the doorposts which are in the place used for storing straw or in the stalls of oxen, in which people do not live and eat. (Cf. Mekhilta and הגהות הגר״א thereon).

And they shall take the blood, and put it on the two side posts and on the upper door post of the houses, in which they shall eat it.

וְלָֽקְחוּ֙ מִן־הַדָּ֔ם וְנָ֥תְנ֛וּ עַל־שְׁתֵּ֥י הַמְּזוּזֹ֖ת וְעַל־הַמַּשְׁק֑וֹף עַ֚ל הַבָּ֣תִּ֔ים אֲשֶׁר־יֹאכְל֥וּ אֹת֖וֹ בָּהֶֽם׃