Technical and linguistic note: In our manuscripts the word here was written "lidatan", but we corrected it according to the standard usage (al-jaddah) from the repeated occurrence of this narration (no. 4228), where the wording is "kunna lidayn" (we were two of the same age). It is likewise in al-Bayhaqi's "Dala'il al-Nubuwwah" (1/ 76) from al-Hakim and in the other narrations of Ibn Ishaq.
Linguistic research: Qasim bin Thabit al-Saraqusti says in "al-Dala'il 'ala Ma'ani al-Hadith" (2/ 786) that the Arabs say "lidan" in the dual, because they make the dual additions (alif and nun) stand in place of the omitted ha' (ta' marbutah), just as they say "alyan" and "khusyan". We (the editors) say: al-Jawhari also said in "al-Sihah" (2/ 554) that "lidan" is what is said. Therefore Abu Dharr al-Khushani's statement in "Sharh Gharib al-Siyar" (1/ 54) that "the well-known usage is 'lidatan' (with ta')" is not correct.