Saad bin Abu Waqqas reported, "The Messenger of Allah ﷺ visited me during the Farewell Pilgrimage when I was suffering from an illness that had brought me to the brink of death. I said, 'Messenger of Allah, you can see how severe my pain has become. I am a man of wealth, and no one will inherit from me except a single daughter. Shall I give away two-thirds of my wealth in charity?'He replied, 'No.'I asked, 'Then half of it?'He said, 'No. A third, and a third is plenty. To leave your heirs wealthy is better than to leave them destitute, begging from people. You will not spend anything seeking the face of Allah without being rewarded for it, even the morsel you place in your wife's mouth.'I asked, 'Messenger of Allah, will I be left behind after my companions?'He answered, 'You will not be left behind to perform any deed seeking the face of Allah without being raised in rank and degree because of it. Perhaps you will be left behind so that some people may benefit through you and others may be harmed by you. O Allah, complete the migration of my companions and do not turn them back on their heels. But the unfortunate one is Saad bin Khawla.'"The Messenger of Allah ﷺ grieved for him because he had died in Makkah.
عادني رسول الله ﷺ في حجة الوداع من وجع أشفيت منه على الموت، فقلت: يا رسول الله بلغني ما ترى من الوجع، وأنا ذو مال، ولا يرثني إلا ابنة لي واحدة، أفأتصدق بثلثي مالي؟ قال: لا. قال: قلت: أفأتصدق بشطره؟ قال: لا، الثلث والثلث كثير، إنك أن تذر ورثتك أغنياء خير من أن تذرهم عالة يتكففون الناس، ولست تنفق نفقة تبتغي بها وجه الله، إلا أجرت بها، حتى اللقمة تجعلها في في امرأتك. قال: قلت: يا رسول الله، أخلف بعد أصحابي؟ قال: إنك لن تخلف فتعمل عملا تبتغي به وجه الله إلا ازددت به درجة ورفعة، ولعلك تخلف حتى ينفع بك أقوام، ويضر بك آخرون. اللهم أمض لأصحابي هجرتهم، ولا تردهم على أعقابهم. لكن البائس سعد بن خولة. قال: رثى له رسول الله ﷺ من أن توفي بمكة.
Bukhari narrated it in "The Virtues of the Ansar" (3936), and Muslim in "Bequests" (1628), both by way of Ibrahim bin Saad, from Ibn Shihab, from Amir bin Saad, from his father Saad bin Abu Waqqas, who related it.His statement, "Perhaps you will be spared so that peoples may benefit through you..." means that you will not die from this illness but will remain alive. So he lived after that until he conquered Iraq and other lands, and the Muslims benefited through him while the disbelievers were harmed by him, as he conquered Qadisiyyah during the caliphate of Umar bin Khattab.