“Jesus said to them, ‘Truly, truly, I say to you, before Abraham was, I am.'” (John 8:58)
The burning bush scene and Isaiah’s “I am” statement’s are often proposed as the background for this, and rightly so. But I think there may also be a contrast present here that has already appeared in John’s Gospel. John sets up a distinction here between γινομαι and ειμι: Before Abraham was (πριν Αβρααμ γενεσθαι) I am (εγω ειμι). This may be an allusion to John’s Prologue:
In the beginning was (ην, from ειμι) the Word (v. 1).
All things were made (εγενετο, from γινομαι) through him (v. 3).
John seems to contrast the preexistent, eternal character of the Word (using ειμι) with the temporal, created nature of everything else (γινομαι). So when we get to chapter 8, Jesus locates Abraham in the realm of created and temporal (γινομαι), and himself as preexistent and divine (ειμι).
I haven’t checked any commentaries on this, so I’m probably just late to the game here. But it stuck out to me for the first time today.