WHEN TO OFFER VOLUNTARY PRAYERS H 1117 "I (Ibn Omar) offered, in the company of the Messenger of Allah, praise and peace be upon him, two voluntary units of prayer (rak'a) before the mid-day prayer and two voluntary units of prayer after it, and two units of voluntary prayer after the Friday prayer; two after the sunset prayer and two after the night (isha) prayer. R 1117 Bukhari and Muslim with a chain up to ibn Omar who related this.
1098- وعن ابن عمر رَضِيَ اللهُ عَنهُما ، قَالَ : صَلَّيْتُ مَعَ رَسُولِ اللهِ صلى الله عليه وآله وسلم ، رَكْعَتَيْنِ قَبْلَ الظُّهْرِ، وَرَكْعَتْينِ بَعْدَهَا، وَرَكْعَتَيْنِ بَعْدَ الجُمُعَةِ ، وَرَكْعَتَينِ بَعدَ المَغْرِبِ ، وَرَكْعَتَينِ بَعدَ العِشَاءِ . متفقٌ عَلَيهِ .