Genesis:  22:3 –And Abraham arose early in the morning, and he saddled his donkey, and he took his two young men with him and Isaac his son; and he split wood for a burnt offering, and he arose and went to the place of which God had told him.

Babylonian Talmud – Pesachim 4a: – The whole day is a valid time for performing circumcisions, but one should [optimally] perform circumcisions earlier in the day. This is because of the dictum “Zealous people should perform mitzvot with alacrity otherwise physical aspects will present themselves to prevent performing the mitzvah” [Zrizim makdimim l’mitzvot]

Torah Temimah Colloquial Translation on Note #7:

Note what is written above in Genesis 21:4 to explain the phrase “Abraham performed the circumcision [in the manner] as God had commanded him”. According what is stated in Gemora Kedushin 29a: that the commandment of alacrity for circumcision is biblical in nature [not rabbinic] and applies to all of Israel. [If that is so], then the phrase “zealous people should…” is problematic. In the book Ravid HaZahav, the author asks why the issue of “zealous people should perform the commandment early” is not deduced from the verse in Parshat Bo (Exodus 12:17) “and you shall zealously observe my commandments”. There, on that verse, the Gemora and the Mechilta do deduce that if an opportunity comes into your hand to do a commandment, one should not be lax / lazy in performing it.

The answer appears to me that here, the Torah is commanding to perform the mitzvot and the Gemora is bringing a proof that zealous people, due to their love of the commandments, will perform them sooner / earlier of their own initiative [rather than as a core part of the obligation]. It is this point that the Gemora here is trying to prove by quoting the verse of Abraham arising early in the morning [even though it wasn’t a ‘legal’ obligation to do so, per se.]

Regarding the legal details of “zealous people should perform the commandments with alacrity”, we will, with God’s help, delve more deeply into that topic in our comments on Exodus 12:17.

Translator’s  Note: The Torah Temimah is distinguishing between the times when getting up early to do a commandment is a legal obligation versus the times when doing so reflects our love of the commandments.