And behold, according to our interpretation, Pharaoh's language of granting this permission is very precise – “Behold, you are in your own authority, behold, you are free people” – which is the language of a slave's bill of release, as we have learned in the Mishnah (Gittin 85b): "The essence of a bill of release is, 'Behold, you are a free woman, behold, you are for yourself'" – since, according to our interpretation, the entire purpose of this permission was the nullification of the ownership of slavery, it must necessarily be given in a language effective for that purpose.

However, from another perspective, it is surprising, as from the language of the Midrash (Yalkut Shimoni, Remez 208), it appears that this permission from Pharaoh was given merely verbally, as it is found there: "Moses said to Pharaoh, 'And if you wish to remove this plague from you – say: 'Behold, you are in your own authority, behold, you are servants of the Holy One, blessed be He.' Pharaoh began to shout: 'Previously you were my slaves, but now behold, you are free people, behold, you are in your own authority.' You need to praise the Holy One, blessed be He, that you are His servants, as it is said (Psalms 113:1), 'Hallelujah, praise the servants of the Lord,'" end quote. And according to our understanding, if the purpose of this permission was to nullify the ownership of slavery, then for this purpose, a mere verbal statement is not sufficient, rather a written document is required, as the Rambam states (Chapter 2 of the Laws of Slaves, Halacha 11): "A master who forgives his slave the money that remains for him to work off is not forgiven until he writes him a bill of release. How so? If he bought him for sixty, and the slave worked for a year or two, and the master said to him, 'The remaining money is forgiven to you, go your way,' he is not released from his enslavement until he writes him a bill," end quote.

Indeed, from the words of the Or HaChaim, it appears that it was obvious to him that this was done through a written document. See his words on the verse: "And it was told to the king of Egypt that the people had fled, and the heart of Pharaoh and his servants was turned against the people, and they said, 'What is this that we have done, that we have let Israel go from serving us?'" – he raised several points: Firstly, on the statement 'that they had fled,' and not 'that they had left,' which indicates that they saw it as an act of fleeing. Secondly, on the statement 'the heart of Pharaoh and his servants was turned,' which implies that they regretted what they had done, and the matter is puzzling, for did they do it willingly? Were they not struck by great plagues until they almost perished, and against their will they sent them out, so how could their hearts turn over a matter they did unwillingly? Thirdly, on their statement 'What is this that we have done,' as if complaining about doing something improper, yet they did it against their will, so why should a person complain about something done against his will?

The Or HaChaim explained that 'the people' mentioned here, who fled, and whose hearts Pharaoh and his servants turned against, were not the Israelites, but rather the mixed multitude, as explained in the Zohar (Part 2, 45b). He further explained that the mixed multitude's departure with Israel was a cunning scheme of Pharaoh's, who sought to control Israel through them, to bring them back to Egypt after the three days of sacrificial worship. However, they, instead of fulfilling Pharaoh's mission to force Israel to return, betrayed him, fled, and joined Israel. From now on, says the Or HaChaim, this is the interpretation of the verse: 'It was told to the king of Egypt that the people had fled' – meaning, the people that Pharaoh himself sent with Israel to bring them back, now they fled and went away, and to them, the language 'that they fled' applies, because without fleeing, they could not escape from Pharaoh, as they were his people and servants. 'The heart of Pharaoh and his servants was turned against the people' – meaning, they regretted sending these mixed multitude, who were probably the lowest in Egypt, upon whom the king's labor and all despicable work fell, and now in their fleeing, the remaining 'elite' would have to fill their place. Thus far, the words of Pharaoh and his servants about the mixed multitude.

Now they turn to speak about Israel, saying: 'What is this that we have done' – meaning, we are amazed at our actions in sending the people. The Or HaChaim explains the reason for their amazement – and this is relevant to our matter: 'That we have let Israel go from serving us' – meaning, as our sages have stated, that Pharaoh wrote a bill of release to Israel and said to them, 'Behold, you are for yourselves, behold, you are free people,' and this is what he says, 'we have let go' – with a bill of release, 'from serving us' – that they no longer have the status of slaves. Since they were released with a bill, even if they might consider returning, they would no longer be subject to servitude as slaves, and since this is the case, the necessary labor for the king would fall upon the common people, the mixed multitude, who had fled, so who would work? Therefore, they immediately prepared to pursue, end quote from the Or HaChaim.

From his words, it is clear that it was obvious to him that it was not merely a verbal statement that Pharaoh said to them 'Behold, you are for yourselves, behold, you are free people,' but rather he inscribed it on a scroll, and a bill of release was given from his hand to the Israelites.

Moreover, it can be said that specifically a Canaanite slave of an Israelite does not go free with a mere verbal statement but requires a bill of release, but an Israelite sold to a gentile goes free even with a mere verbal statement, as is the opinion of the Ramban and the Ritva in Yevamot (46a). This is not the place to elaborate further.