דֶּ֚רֶךְ שְׁלֹ֣שֶׁת יָמִ֔ים נֵלֵ֖ךְ בַּמִּדְבָּ֑ר וְזָבַ֙חְנוּ֙ לַֽיהוָ֣ה אֱלֹהֵ֔ינוּ כַּאֲשֶׁ֖ר יֹאמַ֥ר אֵלֵֽינוּ׃
Мы пойдем три дня'Путешествие в пустыню и жертва Господу Богу нашему, как Он заповедует нам.'
Chizkuni
וישבו, “so that they shall turn back;” G-d said that He did not want the Egyptians to be able to say that Moses and Aaron had deceived him when they said that all they had requested was to travel three days into the desert (Exodus 8,23).
Sforno
כי ברח העם, they had not marched straight into the desert as they had maintained they would. In 8,23 all they had asked for was to be allowed to march into the desert a distance of three days’ journey. They had now departed from their planned route so that this could be interpreted as an attempt to flee. The new route made no sense, showing they did not know where they were headed, just as one would expect of a fugitive.