Allah said:

﴿وَقَـتِلُواْ فِي سَبِيلِ اللَّهِ وَاعْلَمُواْ أَنَّ اللَّهَ سَمِيعٌ عَلِيمٌ ﴾

(And fight in the way of Allah and know that Allah is All-Hearer, All-Knower.)

This Ayah indicates that just as caution does not alter destiny, abandoning Jihad will neither bring the appointed term closer nor delay it. Rather, destiny and the appointed provisions are fixed and shall never be changed or altered, neither by addition nor deletion. Similarly, Allah said:

﴿الَّذِينَ قَالُواْ لإِخْوَنِهِمْ وَقَعَدُواْ لَوْ أَطَاعُونَا مَا قُتِلُوا قُلْ فَادْرَءُوا عَنْ أَنفُسِكُمُ الْمَوْتَ إِن كُنتُمْ صَـدِقِينَ ﴾

((They are) the ones who said about their killed brethren while they themselves sat (at home): "If only they had listened to us, they would not have been killed.'' Say: "Avert death from your own selves, if you speak the truth.'') (3:168)

Allah said:

﴿وَقَالُواْ رَبَّنَا لِمَ كَتَبْتَ عَلَيْنَا الْقِتَالَ لَوْلا أَخَّرْتَنَا إِلَى أَجَلٍ قَرِيبٍ قُلْ مَتَـعُ الدُّنْيَا قَلِيلٌ وَالاٌّخِرَةُ خَيْرٌ لِّمَنِ اتَّقَى وَلاَ تُظْلَمُونَ فَتِيلاًأَيْنَمَا تَكُونُواْ يُدْرِككُّمُ الْمَوْتُ وَلَوْ كُنتُمْ فِى بُرُوجٍ مُّشَيَّدَةٍ﴾

(They say: "Our Lord! Why have you ordained for us fighting Would that you had granted us respite for a short period'' Say: "Short is the enjoyment of this world. The Hereafter is (far) better for him who fears Allah, and you shall not be dealt with unjustly even equal to the Fatila (a scalish thread in the long slit of a date stone). Wheresoever you may be, death will overtake you even if you are in fortresses built up strong and high!'') (4:77, 78)

Abu Sulayman, Khalid bin Al-Walid, the commander of the Muslim armies, the veteran among Muslim soldiers, the protector of Islam and the Sword of Allah that was raised above His enemies, said while dying, "I have participated in so-and-so number of battles. There is not a part of my body, but suffered a shot (of an arrow), a stab (of a spear) or a strike (of a sword). Yet, here I am, I die on my bed just as the camel dies! May the eyes of the cowards never taste sleep.'' He, may Allah be pleased with him, was sorry and in pain because he did not die as martyr in battle. He was sad that he had to die on his bed!