An expedition of the Ansar was operating in Persia with their leader. 'Umar used to send expeditions by turns every year, but he neglected them. When the expired, the people of expedition appointed on the frontier came back. He ('Umar) took serious action against them and threatened them, though they were the Companions of the Messenger of Allah ﷺ. They said: 'Umar you neglected us, and abandoned the practice for which the Messenger of Allah ﷺ commanded to send the detachments by turns.  

أَنَّ جَيْشًا مِنَ الأَنْصَارِ كَانُوا بِأَرْضِ فَارِسَ مَعَ أَمِيرِهِمْ وَكَانَ عُمَرُ يُعْقِبُ الْجُيُوشَ فِي كُلِّ عَامٍ فَشُغِلَ عَنْهُمْ عُمَرُ فَلَمَّا مَرَّ الأَجَلُ قَفَلَ أَهْلُ ذَلِكَ الثَّغْرِ فَاشْتَدَّ عَلَيْهِمْ وَتَوَاعَدَهُمْ وَهُمْ أَصْحَابُ رَسُولِ اللَّهِ ﷺ فَقَالُوا يَا عُمَرُ إِنَّكَ غَفَلْتَ عَنَّا وَتَرَكْتَ فِينَا الَّذِي أَمَرَ بِهِ رَسُولُ اللَّهِ ﷺ مِنْ إِعْقَابِ بَعْضِ الْغَزِيَّةِ بَعْضًا  

A son of Adi ibn Adi al-Kindi said that Umar ibn AbdulAziz wrote (to his governors): If anyone asks about the places where spoils (fay') should be spent, that should be done in accordance with the decision made by Umar ibn al-Khattab (Allah be pleased with him). The believers considered him to be just, according to the saying of the Prophet ﷺ: Allah has placed truth upon Umar's tongue and heart. He fixed stipends for Muslims, and provided protection for the people of other religions by levying jizyah (poll-tax) on them, deducting no fifth from it, nor taking it as booty.  

عَنْ مَوَاضِعِ الْفَىْءِ فَهُوَ مَا حَكَمَ فِيهِ عُمَرُ بْنُ الْخَطَّابِ ؓ فَرَآهُ الْمُؤْمِنُونَ عَدْلاً مُوَافِقًا لِقَوْلِ النَّبِيِّ ﷺ جَعَلَ اللَّهُ الْحَقَّ عَلَى لِسَانِ عُمَرَ وَقَلْبِهِ فَرَضَ الأَعْطِيَةَ وَعَقَدَ لأَهْلِ الأَدْيَانِ ذِمَّةً بِمَا فُرِضَ عَلَيْهِمْ مِنَ الْجِزْيَةِ لَمْ يَضْرِبْ فِيهَا بِخُمُسٍ وَلاَ مَغْنَمٍ  

I heard the Messenger of Allah ﷺ say: Allah, the Exalted, has placed truth on Umar's tongue and he speaks it.  

سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ إِنَّ اللَّهَ وَضَعَ الْحَقَّ عَلَى لِسَانِ عُمَرَ يَقُولُ بِهِ