Chapter on the Reasons Behind Hajj
Man Lā Yaḥḍuruh al-Faqīh|Volume 2|Book 3|Chapter 1
وَ سُمِّيَ اَلْخَيْفُ خَيْفاً لِأَنَّهُ مُرْتَفِعٌ عَنِ اَلْوَادِي وَ كُلُّ مَا اِرْتَفَعَ عَنِ اَلْوَادِي سُمِّيَ خَيْفاً ».
"It was named Al-Khaif because it is elevated above the valley, and everything that rises above the valley is called 'Khaif.'"
- Ṣaḥīḥ al-Faqīh