It is narrated from a man of Banu Tamim that the Messenger of Allah (peace and blessings be upon him) said: "When one of you fears that he will forget (something or some knowledge), let him recite this supplication: 'Al-hamdu lillahi mudhakkiri al-nasi' (All praise is for Allah, who reminds the one who forgets)."
The chain of this hadith is da'if (weak), because one of its narrators, Mu'awiyah bin Yahya, is weak, and the man of Banu Tamim from whom he narrated is majhul (unknown).
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب العلم / 3045
Hadith Gradingمحدثین:إسناده ضعيف
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :إسناده ضعيف. » «انفرد به المصنف من هذا الطريق»