Ruhullah Al-Khumaini writes:

ولا مجال للشك في دلالة الرواية على ولاية الفقيه وخلافته في جميع الشؤون والخلافة الواردة في جملة اللهم ارحم خلفائي لا يختلف مفهومها في شيء عن الخلافة التي تستعمل في جملة علي خليفتي

“There is no doubt that the tradition proves the leadership of the legal scholar (Khumaini) and his succession (Khilafah) in all matters and the succession in the sentence: “God, have mercy on my successors.” Does not differ from their understanding in any way from the succession (Khilafah), which was used in the sentence: “Ali is my successor!” [Al-Hukumat-ul-Islamiyyah, pg. 61]