It was narrated from ‘Umar that he had vowed during the days of Ignorance to spend one night in I’tikaf. He asked the Prophet ﷺ about it, so he commanded him to spend it in I’tikaf. (Using translation from Ibn Mājah 1772)  

أَنَّهُ كَانَ عَلَيْهِ لَيْلَةٌ نَذْرٌ فِي الْجَاهِلِيَّةِ يَعْتَكِفُهَا فَسَأَلَ رَسُولَ اللهِ ﷺ «فَأَمَرَهُ أَنْ يَعْتَكِفَ»  

"Umar had made a vow to spend a night in 'Itikaf in Al-Masjid Al-Haram. He asked the Messenger of Allah about that, and he ordered him to perform the 'Itikaf." (Using translation from Nasāʾī 3821)   

كَانَ عَلَى عُمَرَ بْنِ الْخَطَّابِ نَذْرٌ فِي اعْتِكَافِ لَيْلَةٍ فِي الْمَسْجِدِ الْحَرَامِ فَسَأَلَ رَسُولَ اللهِ ﷺ «فَأَمَرَهُ أَنْ يَعْتَكِفَ»  

It was narrated from Ibn 'Umar that 'Umar had vowed -during the Jahiliyyah- to spend a day in 'Itikaf. He asked the Messenger of Allah about that, and he commanded him to perform the 'Itikaf. (Using translation from Nasāʾī 3822)  

أَنَّ عُمَرَ كَانَ قَدْ جَعَلَ عَلَيْهِ يَوْمًا يَعْتَكِفُهُ فِي الْجَاهِلِيَّةِ فَسَأَلَ رَسُولَ اللهِ ﷺ عَنْ ذَلِكَ «فَأَمَرَهُ أَنْ يَعْتَكِفَ»  

"O Messenger of Allah! I want to give all my wealth in charity for Allah and His Messenger." The Messenger of Allah said to him: "Keep some of your wealth for yourself; that is better for you." (Using translation from Nasāʾī 3823)   

أَنَّهُ قَالَ لِرَسُولِ اللهِ ﷺ حِينَ تِيبَ عَلَيْهِ يَا رَسُولَ اللهِ إِنِّي أَنْخَلِعُ مِنْ مَالِي صَدَقَةً إِلَى اللهِ وَرَسُولِهِ فَقَالَ لَهُ رَسُولُ اللهِ ﷺ «أَمْسِكْ عَلَيْكَ بَعْضَ مَالِكَ فَهُوَ خَيْرٌ لَكَ» قَالَ لَنَا أَبُو عَبْدِ الرَّحْمَنِ يُشْبِهُ أَنْ يَكُونَ الزُّهْرِيُّ سَمِعَ هَذَا الْحَدِيثَ مِنْ عَبْدِ اللهِ بْنِ كَعْبِ بْنِ مَالِكٍ وَسَمِعَهُ مِنْ عَبْدِ الرَّحْمَنِ بْنِ عَبْدِ اللهِ عَنْهُ فِي الْحَدِيثِ الطَّوِيلِ