January 4

As regards the questions you have asked, as Bahá’u’lláh says categorically that God commanded Abraham to offer up Ismá’íl, as far as we are concerned, it is Ismá’íl who was the intended sacrifice.

In view of the great antiquity of Genesis, it is quite possible that at some period the names were changed, and the error was propagated.
Whatever happened, we Bahá’ís must follow the words in our own Scriptures as being the most authentic. 
- Shoghi Effendi  (From a letter dated 6 March 1955 written on behalf of Shoghi Effendi to an individual believer; ‘Unfolding Destiny’)