"That you may settle yourselves upon their backs," meaning the backs of what He has subjected to you; that is, that you may ride them.
"And we could not have brought them under our control," meaning: we would not have been able to handle them. He said: You say, 'I am muqrin (capable) for you,' meaning: I am able to handle you. It is also said that the derivation of the term is from their saying, 'I am a qirn (peer) to so-and-so,' when I am like him in strength. If you mean age, you say qarnuhu, with a fathah on the qaf.
﴿لتستووا على ظُهُوره﴾ ظُهُور مَا سخر لكم؛ أَي: تركبوه.
﴿وَمَا كُنَّا لَهُ مُقْرِنِينَ﴾ يَعْنِي: مطيقين , قَالَ: تَقول: أَنا مقرنٌ لَك؛ أَي مطيقٌ لَك؛ وَقيل: إِن اشتقاق اللَّفْظَة من قَوْلهم: أَنا قِرْنٌ لفُلَان إِذا كنت مثله فِي الشدَّة , فَإِذا أردْت السنّ قلت: قَرْنُه بِفَتْح الْقَاف.
