﴾فَضْلُ اللَّهِ﴿ “The favour of Allah”
The word favour means increase, meaning what is above the norm, as Allah has said about the righteous martyrs, and this is good news from Allah:
﴿وَلَا تَحْسَبَنَّ الَّذِينَ قُتِلُوا فِي سَبِيلِ اللَّهِ أَمْوَاتًا ۚ بَلْ أَحْيَاءٌ عِندَ رَبِّهِمْ يُرْزَقُونَ (١٦٩) فَرِحِينَ بِمَا آتَاهُمُ اللَّهُ مِن فَضْلِهِ وَيَسْتَبْشِرُونَ بِالَّذِينَ لَمْ يَلْحَقُوا بِهِم مِّنْ خَلْفِهِمْ أَلَّا خَوْفٌ عَلَيْهِمْ وَلَا هُمْ يَحْزَنُونَ (١٧٠)﴾
“And never think of those who have been killed in the cause of Allah as dead. Rather, they are alive with their Lord, receiving provision, Rejoicing in what Allah has bestowed upon them of His bounty, and they receive good tidings about those [to be martyred] after them who have not yet joined them – that there will be no fear concerning them, nor will they grieve.” [Surah Ali ‘Imran: 169 -170].
This means that they are pleased by the bounty of Allah and not by His justice, and that bounty is above justice. Justice is to take exactly in the same measure to what you did while bounty it is to take more than what a person did.