It is narrated from Mus'ab bin Sa'd bin Abi Waqqas (may Allah have mercy on him) that the Mother of the Believers, Sayyidah Hafsah bint Umar (may Allah be pleased with them both), said to Sayyiduna Umar bin al-Khattab (may Allah be pleased with him): "If only you would wear clothes softer and finer than these present clothes of yours, and eat food better and softer than this food of yours!" Sayyiduna Umar (may Allah be pleased with him) said (in reply to her sympathetic suggestion): "I put you (for this decision) before your own self (so that you yourself may judge fairly). Do you not know such-and-such about the (ascetic and hard) life of the Messenger of Allah (peace and blessings be upon him) and Abu Bakr (may Allah be pleased with him)?" (He kept reminding her of the details of the simple life of the Messenger of Allah (peace and blessings be upon him)) until Sayyidah Hafsah (may Allah be pleased with her) began to weep. Then Sayyiduna Umar (may Allah be pleased with him) said: "I have explained (my view) to you. The truth is that I want to share with the two of them in their hard and toilsome life (in this world), so that I may also gain their company in that pleasant and delightful life (of the Hereafter)."
Imam al-Nasa'i narrated it in al-Sunan al-Kubra through Suwayd bin Nasr, Ibn al-Mubarak, Isma'il and his brother al-Nu'man.
So if Mus'ab bin Sa'd heard this narration directly from Sayyidah Hafsah (may Allah be pleased with her), then this hadith is sahih; otherwise it is mursal, but its chain is sahih.
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب الرقائق / 3156
Hadith Gradingمحدثین:إسناده صحيح، مرسل
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :قال ابن حجر: فَإِنْ كَانَ مُصْعَبٌ سَمِعَهُ مِنْ حَفْصَةَ رَضِيَ اللهُ عَنْهُمَا فَهُوَ صَحِيحٌ ، وَإِلَّا فَهُوَ مُرْسَلٌ صَحِيحُ الْإِسْنَادِ . » «أخرجه الأحاديث المختارة للضياء برقم: 111، وأخرجه المستدرك للحاكم برقم: 423، وأخرجه السنن الكبرى للنسائي برقم: 11806، وأخرجه المنتخب من مسند عبد بن حميد برقم: 25، وأخرجه مصنف ابن أبي شيبة برقم: 35475»