Second and third person at beginning of Mishpatim

Question

The start of Mishpatim (Exodus 21:2-6) discusses the Hebrew slave. It starts with "Ki sikneh eved ivri" - "When you will buy a Hebrew slave", referring to the master in the second person. The remainder of passage uses the the third person for the master, as in "Im adonav yiten lo isha" - "If his master will give him a wife". Why the change?

Answer 1

Sifrei says in Deuteronomy Re'eh:

מנין כשאתה קונה לא תהא קונה אלא עבד עברי שנאמר כי תקנה עבד עברי

^{From where [do we know] when you buy [a slave] you should only buy a Hebrew slave? As it says: 'When you shall buy a Hebrew slave.}

Ohr Hachaim explains very similarly in Exodus on our verse (The Birchas Shimon, who comments on the Ohr Hachaim, points this out, citing the Sifrei):

^{Perhaps that it means to say that if it will be before him to buy a Canaanite slave and a Hebrew slave, he should prioritize the Hebrew, and that is the measure of the verse, when you will want to buy a slave, prioritize buying a Hebrew, and don't say 'I will buy a slave that I will work with him forever, and I will not buy a slave that after six years I will send him off'...}

It seems like the direct language is being expounded upon, as opposed to a more incidental 'If a man shall buy a Hebrew slave...'

This interpretation is further reinforced, in my opinion by the cantillation marks. Over the word, תקנה‏, you shall acquire, we find a Pashta, a distinctive mark of the second degree, meaning that it enforces a moderate pause in the verse, making it read like so (number of commas indicate strength of pause):

,,,,כי תקנה,, עבד עברי,,, שש שנים,,, יעבד,,,, ובשביעית,,, יצא לחפשי,,, חנם‏

^{When you shall acquire ,, a Hebrew servant ,,, six years ,,, he shall serve ,,,, and on the seventh ,,, he shall go free ,,, free of charge ,,,,}

That pause could cause the verse to be read:

^{When you shall acquire [a slave, it should be] a Hebrew slave}