Round table

Question regarding point 5.6 of the online game rules for HoMMIII: <5.6. Hit-and-run is prohibited: the attacking hero is not allowed to retreat in the first round of battle if they have used combat magic or any other magic that, in any way, has inflicted any damage on the opponent. This prohibition does not apply to the hero who is defending.> Player A attacked Player B, and in the first round, cast an explosion spell. Player B resisted it. Does Player A have the right to surrender in the first round after the resistance? If we interpret the rules literally, since no damage was inflicted on the opponent, does that mean they can? Please explain; I'm a bit confused. Thank you in advance. :)