The diplomatic negotiations between Moses and Pharaoh reach a breaking point over the terms of the Israelites' departure. Moses adamantly refuses to leave any collateral in Egypt to guarantee their return. The exodus must be absolute and uncompromising, driven by an unconditional commitment to God's future demands. Every single Israelite must take all their property, including massive herds of livestock numbering in the hundreds [העמק דבר]. The insistence that not a single hoof will remain is a poetic exaggeration emphasizing that absolutely nothing will be left behind [אם למקרא, קאסוטו, נתינה לגר]. This sweeping standard encompasses every type of animal, including non-kosher beasts like horses, donkeys, and camels [רש״י, מזרחי, אור החיים].
Taking non-kosher animals raises a practical question, as they cannot be offered as sacrifices. However, their inclusion serves an economic purpose. These animals can be sold or traded to purchase the necessities and sacrificial offerings required for God's service [אור החיים, פרדס יוסף]. On a more conceptual level, observing these animals and their natural traits can teach the Israelites valuable lessons on how to properly serve God [פרדס יוסף].
The central justification for taking all their possessions lies in a profound uncertainty regarding what God will ultimately require. Moses's assertion that they do not yet know how they will serve God effectively shuts down any argument Pharaoh might use to keep a portion of the livestock in Egypt [שפתי כהן]. The primary approach among commentators is that this uncertainty involves the specific type, age, and quantity of the sacrifices. Without knowing whether God will choose a bull or a sheep, or how many He will demand, the Israelites must take everything to ensure they are prepared for any request [אבן עזרא, העמק דבר, שד״ל, ביאור שטיינזלץ].
Other perspectives suggest the uncertainty relates to the sheer volume of the required service, with the Israelites fearing God might demand more than they currently possess [רש״י, מזרחי]. While God does not make impossible demands of His creatures, if the Israelites were to willingly leave animals behind and subsequently fall short, it would be viewed as deliberate negligence rather than an unavoidable circumstance [משכיל לדוד]. The uncertainty might even extend to the very nature of the worship itself. God might not ask for animal sacrifices at all, but instead desire service of the heart through prayer [דברי דוד]. Alternatively, He might command the construction of a Tabernacle, requiring gold and precious stones that would need to be acquired by trading their livestock [אור החיים]. A completely different approach interprets this uncertainty through the lens of subjugation. The Israelites do not yet know what they will transform into a servant for God. The very animals that the Egyptians worshipped as deities will be taken and entirely subjugated to serve God's purposes [רש״ר הירש].
Ultimately, the exact details of their worship will remain a mystery until they reach their final destination in the wilderness at Mount Sinai [אבן עזרא, ביאור שטיינזלץ]. Beyond the practical reality of waiting for divine instruction, Moses signals to Pharaoh a fundamental principle of faith: it is inappropriate and immoral to demand that God detail His desires in advance before they have even arrived at the designated place of worship [אור החיים].