The law of redemption of the firstborn in Exod. 13:13–16  is linked by the topos of teaching the law to the Shema (Deut. 6:4–10), which shares with it the topos of teaching (Exod. 13:14; Deut. 6:7), the words לאות על־ידך, as a sign on your hand (Exod. 13:16; Deut. 6:8), and לטטפת בין עיניך, and as a headband between your eyes (Exod. 13:16; Deut. 6:8).  The linkage implies that the Shema alludes to the redemption of the Israelite firstborn, an implication that is supported by the use of the word מזזות, doorposts (Deut. 6:10), which recalls the way that YHWH saved the Israelites, His firstborn, when He saw the blood on המזוזת, the doorposts (Exod. 12:23).  The proclamation in Deut. 6:4 is a qualitative one, proclaiming that Israelites serve YHWH alone, as Levinson, citing Rashbam, who first alluded to this interpretation, has pointed out (Bernard M. Levinson, “Deuteronomy,” in The Jewish Study Bible, ed. Adele Berlin, Marc Zvi Brettler, Michael Fishbane (Oxford: Oxford University Press, 2004), 379-380, The allusions to the redemption of the firstborn in the Shema highlight the fact that Deut. 6:4, like the rest of the pericope, is a proclamation of loyalty to God alone.