خ ر د لkh-r-d-l
(quadriliteral, rubāʿī) — خَرْدَلkhardal (generic noun, ism jins; singular, wāḥidah, خَرْدَلَةkhardalah): mustard seed; among the Arabs it was the proverbial example of the smallest and most trifling thing, which is why the Quran chose it to express the minuteness of the reckoning of the Hereafter. Twice in the Quran, both times for this purpose: ﴿مِثْقَالَ حَبَّةٍ مِّنْ خَرْدَلٍ﴾ (Al-Anbiyāʾ 21:47; Luqmān 31:16)