وَضَمُّ سُورَةٍ أَوْ ثَلَاثِ آيَاتٍ قِصَارٍ
After al-Fatihah, the Wajib addition is a short Surah or three short verses. The commentary also treats one long verse equal in length to three short verses as sufficient.
This Wajib addition applies:
• in the required recitation rak'ahs of Fard prayer;
• in every rak'ah of Witr;
• in every rak'ah of Nafl prayer.