"We will attend to you, O you two heavy ones [thaqalayn]," meaning jinn and mankind; that is: We will hold you to account and punish you. It is a word of warning, meaning: the polytheists among them.
Muhammad said: The dialect of the people of Hijaz is: faragha, yafrughu—with a damma on the ra'—denoting completion [furughan], whereas Tamim say: faragha, yafradhu—with a fatha on the ra'—denoting [faraghan].
﴿سَنَفْرُغُ لَكُمْ أَيُّهَ الثَّقَلَانِ﴾ الْجِنّ وَالْإِنْس؛ أَي: سنحاسبكم فنعذبكم، وَهِي كلمة وَعِيد؛ يَعْنِي: الْمُشْركين مِنْهُم.
قَالَ محمدٌ: لُغَة أهل الْحجاز: فَرَغ يَفْرُغُ - بِضَم الرَّاء - فُرُوغًا، وَتَمِيم تَقول: فَرَغ يفرَغ - بِفَتْح الرَّاء - فراغا.