Was Abu Bakr stung by a snake in the Cave of Hira during the Prophet's migration?

The story of the snakebite inflicted upon Abu Bakr in the Cave of Thawr during the Hijra (migration) has been mentioned by biographers and historians, such as in "Al-Mishkat" and "Siyar A'lam an-Nubala'". However, its chain of narration (isnad) is weak. This does not definitively mean that the event did not occur.