וּמֵ֣ת כָּל־בְּכוֹר֮ בְּאֶ֣רֶץ מִצְרַיִם֒ מִבְּכ֤וֹר פַּרְעֹה֙ הַיֹּשֵׁ֣ב עַל־כִּסְא֔וֹ עַ֚ד בְּכ֣וֹר הַשִּׁפְחָ֔ה אֲשֶׁ֖ר אַחַ֣ר הָרֵחָ֑יִם וְכֹ֖ל בְּכ֥וֹר בְּהֵמָֽה׃
Setiap anak sulung di tanah Mesir akan mati, mulai dari anak sulung Firaun yang duduk di atas takhtanya sampai kepada anak sulung budak perempuan yang bekerja di belakang batu kilangan, juga setiap anak sulung hewan.
Rashi
עד בכור השבי UNTO THE FIRSTBORN OF THE CAPTIVE (these words are used in 12:29 instead of עד בכור השפחה “unto the firstborn of the handmaid” in this verse) — Why were the captives smitten, for they had not enslaved the Israelites? In order that these might not say that their god had claimed satisfaction for the humiliation imposed upon them and had brought this punishment upon the Egyptians (cf. Mekhilta).
Chizkuni
כל בכור, “every firstborn.” Both the firstborn of a mother and the firstborn of a father were included.
Kli Yakar
Until the firstborn of the maidservant. They raise a difficulty here: Why regarding the actual plague (later, 12:29) does it say until the firstborn of the captive, who is presumably of lesser status than the firstborn of the maidservant? It seems that this is not much of a difficulty, because it’s possible that at the time this prophecy was given, there were not yet captives in Egypt, as this prophecy was given before the first of the month of Nisan, and during this time some of them became captives, and then they were also necessarily struck — both so that [the Egyptians] would not say “their deity avenged their insult,” and because [the captives] had rejoiced at [the Israelites’] misfortune before they were taken captive.