Allah admonishes those who lagged behind the Messenger of Allah in the battle 
of Tabuk, at a time when fruits were ripe and shades tempting in the intense and 
terrible heat,
[يَأَيُّهَا 
الَّذِينَ ءَامَنُواْ مَا لَكُمْ إِذَا قِيلَ لَكُمُ انفِرُواْ فِى سَبِيلِ 
اللَّهِ]
(O you who believe! What is the matter with you, that when you are asked to 
march forth in the cause of Allah), if you are called to perform Jihad in the 
cause of Allah,
[اثَّاقَلْتُمْ إِلَى 
الاٌّرْضِ]
(you cling heavily to the earth), reclining to remain in peace, shade and 
ripe fruits.
[أَرَضِيتُم 
بِالْحَيَوةِ الدُّنْيَا مِنَ الاٌّخِرَةِ]
(Are you pleased with the life of this world rather than the Hereafter), why 
do you do this, is it because you prefer this life instead of the Hereafter 
Allah next diminishes the eagerness for this worldly life and increases it for 
the Hereafter,
[فَمَا مَتَاعُ 
الْحَيَاةِ الدُّنْيَا فِى الاٌّخِرَةِ إِلاَّ قَلِيلٌ]
(But little is the enjoyment of the life of this world compared to the 
Hereafter.) Imam Ahmad recorded that Al-Mustawrid, a member of Bani Fihr, said 
that the Messenger of Allah said,
«مَا الدُّنْيَا فِي 
الْآخِرَةِ إِلَّا كَمَا يَجْعَلُ أَحَدُكُمْ إِصْبَعَهُ هَذِهِ فِي 
الْيَمِّ،فَلْيَنْظُرْ بِمَ تَرْجِعُ؟»
(The life of this world, compared to the Hereafter, is just like when one of 
you dips his finger in the sea, let him contemplate how much of it his finger 
would carry.) The Prophet pointed with his index finger. Muslim collected this 
Hadith. Ath-Thawri narrated that Al-A`mash said about the Ayah,
[فَمَا مَتَاعُ 
الْحَيَاةِ الدُّنْيَا فِى الاٌّخِرَةِ إِلاَّ قَلِيلٌ]
(But little is the enjoyment of the life of this world compared to the 
Hereafter.) "What compares to the provision a traveler takes.'' `Abdul-`Aziz bin 
Abi Hazim narrated that his father said, "When `Abdul-`Aziz bin Marwan was dying 
he said, `Bring the shroud I will be covered with so that I inspect it.' When it 
was placed before him, he looked at it and said, `Is this what I will end up 
with from this life' He then turned his back and cried, while saying, `Woe to 
you, O life! Your abundance is truly little, your little is short lived, we were 
deceived by you.''' Allah warns those who do not join Jihad,
[إِلاَّ تَنفِرُواْ 
يُعَذِّبْكُمْ عَذَابًا أَلِيمًا]
(If you march not forth, He will punish you with a painful torment) Ibn 
`Abbas said, "Allah's Messenger called some Arabs to mobilize, but they lagged 
behind and Allah witheld rain from coming down on them, and this was their 
torment.'' Allah said,
[وَيَسْتَبْدِلْ 
قَوْمًا غَيْرَكُمْ]
(and will replace you by another people), who will give aid to His Prophet 
and establish his religion. Allah said in another Ayah,
[الْفُقَرَآءُ وَإِن 
تَتَوَلَّوْاْ يَسْتَبْدِلْ قَوْماً غَيْرَكُمْ ثُمَّ لاَ يَكُونُواْ]
(And if you turn away (from the obedience to Allah), He will exchange you for 
some other people and they will not be your likes.) [47:38]
[وَلاَ تَضُرُّوهُ 
شَيْئًا]
(and you cannot harm Him at all), you can never harm Allah when you lag 
behind and stay away from joining Jihad,
[وَاللَّهُ عَلَى 
كُلِّ شَيْءٍ قَدِيرٌ]
(and Allah is able to do all things.) He is able to destroy the enemies 
without your help.
[إِلاَّ تَنصُرُوهُ 
فَقَدْ نَصَرَهُ اللَّهُ إِذْ أَخْرَجَهُ الَّذِينَ كَفَرُواْ ثَانِيَ اثْنَيْنِ 
إِذْ هُمَا فِى الْغَارِ إِذْ يَقُولُ لِصَاحِبِهِ لاَ تَحْزَنْ إِنَّ اللَّهَ 
مَعَنَا فَأَنزَلَ اللَّهُ سَكِينَتَهُ عَلَيْهِ وَأَيَّدَهُ بِجُنُودٍ لَّمْ 
تَرَوْهَا وَجَعَلَ كَلِمَةَ الَّذِينَ كَفَرُواْ السُّفْلَى وَكَلِمَةُ اللَّهِ 
هِىَ الْعُلْيَا وَاللَّهُ عَزِيزٌ حَكِيمٌ ]
(40. If you help him (Muhammad ) not (it does not matter), for Allah did 
indeed help him when the disbelievers drove him out, the second of the two; when 
they were both in the cave, he said to his companion: "Be not sad (or afraid), 
surely, Allah is with us.'' Then Allah sent down His Sakinah (calmness, 
tranquillity, peace) upon him, and strengthened him with forces (angels) which 
you saw not, and made the word of those who disbelieved the lowermost, while the 
Word of Allah that became the uppermost; and Allah is All-Mighty, All-Wise.)