ʿUyūn akhbār al-Riḍā
Hadith 229229 - وَبِهذَا الإسناد قالَ: قالَ النَّبِي صَلَّى اللهُ عَلَيْهِوَآلِهِ: يا عَلِيُّ أَنْتَ تَبرَاُ ذَمَّتي، وَأَنْتَ خَلِيفَتِي عَلَى اُمَّتي.
31-229 According to the same documentation, the Prophet (S) said, “O Ali! You will take over my responsibilities. You are my Representative over my nation after me.”