Why was "لَمْ يَكُ شَيْئًا" written in the Holy Qur’an instead of "لَمْ يَكُنْ"?

The omission of the letter "nun" from the jussive imperfect verb of "kana" (to be) is common in the Arabic language. The origin of "lam yak" (he was not) is "lam yakun" (he was not), and the "nun" was omitted for lightness. This omission is permissible, not obligatory. It has appeared in the Holy Quran, poetry, and proverbs in both forms: with and without the omission.