Torah Temimah cites Kiddushin 81b.
“And he did not know and is guilty” — when R’ Akiva reached this verse he would weep… if one who intended to eat chelev and ate chelev [is liable], how much more so.
Homiletic intensification — from the unintended to the intentional.
The verse’s burden on accidental wrongdoing underscores the gravity of intentional transgression. R’ Akiva wept because the Torah already assigns weight to the unintended; the deliberate sinner stands under a far heavier accounting.