It is narrated from al-Hasan al-Basri (may Allah have mercy on him) that the Commander of the Believers, Sayyiduna Umar bin al-Khattab (may Allah be pleased with him), said: "When one of you stands at night (for the Tahajjud prayer) and the words of the Qur'an become heavy upon him (due to being overcome by sleep, that is, his tongue begins to falter and he does not know what he is reciting), then let him sleep."
I (Ibn Hajar) say: The chain of this report is munqati' (broken); however, its basis is found in the two Sahihs (Bukhari and Muslim).
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب النوافل / 608
Hadith Gradingمحدثین:إسناده صحيح، منقطع
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :قال ابن حجر: إِسْنَادُهُ مُنْقَطِعٌ وَأَصْلُهُ فِي الصَّحِيحَيْنِ . » «انفرد به المصنف من هذا الطريق»