Riyad as-Salihin 579
Ubayy bin Ka'b (May Allah be pleased with him) reported:
When one- third of the night would pass, Messenger of Allah (ﷺ) would get up and call out, "O people, remember Allah. The Rajifah (i.e., the first Blowing of the Trumpet which will shake the whole universe and thus cause all life to cease) has come, followed by Ar-Radifah (i.e., the second Blowing of the Trumpet which will restore life and thus mark the Resurrection Day). Death has approached with all that it comprises. Death has approached with all that it comprises." I said: "O Messenger of Allah (ﷺ), I frequently invoke Allah to elevate your rank. How much of my supplications should I devote to you?" He said, "You may devote as much as you wish." When I suggested a quarter, he said, "Do whatever you wish, but it will be better for you if you increase it." I suggested half, and he said, "Do whatever you wish, but it will be better for you if you increase." I suggested two- thirds, and he said, "Do whatever you wish but it will be better for you if you increase it." I said, "Shall I devote all my supplications invoking Allah to elevate your rank?" He said, "Then you will be freed from your worries and your sins will be forgiven." [At- Tirmidhi, who classified it as Hadith Hasan] .
وعن أبي بن كعب رضي الله عنه‏:‏ كان رسول الله صلى الله عليه وسلم‏:‏ إذا ذهب ثلث الليل، قام فقال‏:‏ ‏"‏يا أيها الناس اذكروا الله، جاءت الراجفة، تتبعها الرادفة، جاء الموت بما فيه، جاء الموت بما فيه” قلت‏:‏ يا رسول الله إنى أكثر الصلاة عليك، فكم أجعل لك من صلاتى‏؟‏ قال‏:‏ “ما شئت” قلت‏:‏ الربع‏؟‏ قال‏:‏ “ما شئت، فإن زذت فهو لك” قلت‏:‏ فالنصف‏؟‏ قال‏:‏ ما شئت  فإن زذت فهو لك  قلت ” فالثلثين‏؟‏ قال‏:‏ ما شئت فإن زدت فهو خير لك” قلت‏:‏ أجعل لك صلاتى كلها‏؟‏ قال‏:‏ “إذا تكفى همك، ويغفر لك ذنبك” ‏(‏‏(‏رواه الترمذى وقال‏:‏ حديث حسن‏)‏‏)‏‏.‏