يَا أَيُّهَا الَّذِينَ آمَنُوا مَا لَكُمْ إِذَا قِيلَ لَكُمُ انفِرُوا فِي سَبِيلِ اللَّهِ اثَّاقَلْتُمْ إِلَى الْأَرْضِ ۚ أَرَضِيتُم بِالْحَيَاةِ الدُّنْيَا مِنَ الْآخِرَةِ ۚ فَمَا مَتَاعُ الْحَيَاةِ الدُّنْيَا فِي الْآخِرَةِ إِلَّا قَلِيلٌ
“O you who have believed, what is [the matter] with you that, when you are told to go forth in the cause of Allah, you adhere heavily to the earth? Are you satisfied with the life of this world rather than the Hereafter? But what is the enjoyment of worldly life compared to the Hereafter except a [very] little.”
Part of Surat al-Tawba's unusually blunt command to march, read as evidence Tabuk was commanded directly by Allah.
This ayah is part of Surat al-Tawba's Tabuk-era passage addressing the hypocrites and excuse-makers who stayed behind or mocked the campaign, described at this event.