"And if their turning away" from you, and their denial of you, "is difficult for you, then if you are able to seek a tunnel into the earth," meaning: a passage, that you may enter into it, "or a staircase into the sky," meaning: to the sky, that you may ascend it, "and bring them a sign." This was when they asked for a sign.
Muhammad said: The meaning is: if you are able to do this, then do it; he omitted "then do it" since there was that in the speech which indicated it.
﴿وَإِنْ كَانَ كَبُرَ عَلَيْكَ إِعْرَاضُهُمْ﴾ عَنْكَ، وَتَكْذِيبُهُمْ إِيَّاكَ.
﴿فَإِنِ اسْتَطَعْتَ أَنْ تَبْتَغِيَ نَفَقًا فِي الأَرْضِ﴾ أَيْ: سِرْبًا، فَتَدْخُلَ فِيهِ ﴿أَوْ سلما فِي السَّمَاء﴾ أَيْ: إِلَى السَّمَاءِ، فَتَرْقَى إِلَيْهَا ﴿فتأتيهم بِآيَة﴾ وَهَذَا حِينَ سَأَلُوا الْآيَةَ.
قَالَ مُحَمَّدٌ: الْمَعْنَى: فَإِنِ اسْتَطَعْتَ أَنْ تَفْعَلَ هَذَا فَافْعَلْ؛ اخْتَصَرَ (فَافْعَلْ) إِذْ كَانَ فِي الْكَلَامِ مَا يدل عَلَيْهِ.
