9:111
۞ إِنَّ ٱللَّهَ ٱشْتَرَىٰ مِنَ ٱلْمُؤْمِنِينَ أَنفُسَهُمْ وَأَمْوَٰلَهُم بِأَنَّ لَهُمُ ٱلْجَنَّةَ ۚ يُقَٰتِلُونَ فِى سَبِيلِ ٱللَّهِ فَيَقْتُلُونَ وَيُقْتَلُونَ ۖ وَعْدًا عَلَيْهِ حَقًّۭا فِى ٱلتَّوْرَىٰةِ وَٱلْإِنجِيلِ وَٱلْقُرْءَانِ ۚ وَمَنْ أَوْفَىٰ بِعَهْدِهِۦ مِنَ ٱللَّهِ ۚ فَٱسْتَبْشِرُوا۟ بِبَيْعِكُمُ ٱلَّذِى بَايَعْتُم بِهِۦ ۚ وَذَٰلِكَ هُوَ ٱلْفَوْزُ ٱلْعَظِيمُ
Indeed, Allah has purchased from the believers their lives and their properties [in exchange] for that they will have Paradise. They fight in the cause of Allah, so they kill and are killed. [It is] a true promise [binding] upon Him in the Torah and the Gospel and the Qur'an. And who is truer to his covenant than Allah? So rejoice in your transaction which you have contracted. And it is that which is the great attainment.
Translation · Saheeh International
Tafsir
Ibn Kathīr (abridged)
Allah has purchased the Souls and Wealth of the Mujahidin in Return for Paradise
Allah states that He has compensated His believing servants for their lives and wealth -- if they give them up in His cause -- with Paradise. This demonstrates Allah's favor, generosity and bounty, for He has accepted the good that He already owns and bestowed, as a price from His faithful servants. Al-Hasan Al-Basri and Qatadah commented, "By Allah! Allah has purchased them and raised their worth." Shimr bin `Atiyyah said, "There is not a Muslim but has on his neck a sale that he must conduct with Allah; he either fulfills its terms or dies without doing that." He then recited this Ayah. This is why those who fight in the cause of Allah are said to have conducted the sale with Allah, meaning, accepted and fulfilled his covenant. Allah's statement,
يُقَـتِلُونَ فِى سَبِيلِ اللَّهِ فَيَقْتُلُونَ وَيُقْتَلُونَ
(They fight in Allah's cause, so they kill and are killed.) indicates that whether they were killed or they kill the enemy, or both, then Paradise will be theirs. The Two Sahihs recorded the Hadith,
«وَتَكَفَّلَ اللهُ لِمَنْ خَرَجَ فِي سَبِيلِهِ لَا يُخْرِجُهُ إِلَّا جِهَادٌ فِي سَبِيلِي وَتَصْدِيقٌ بِرُسُلِي بِأَنْ تَوَفَّاهُ أَنْ يُدْخِلَهُ الْجَنَّةَ، أَوْ يَرْجِعَهُ إِلَى مَنْزِلِهِ الَّذِي خَرَجَ مِنْهُ، نَائِلًا مَا نَالَ مِنْ أَجْرٍ أَوْ غَنِيمَة»
(Allah has made a promise to the person who goes out (to fight) in His cause; `And nothing compels him to do so except Jihad = in My Cause and belief in My Messengers. ' He will either be admitted to Paradise if he dies, or compensated by Allah, either with a reward or booty if He returns him to the home which he departed from.) Allah's statement,