It is narrated from Sayyiduna Sahl bin Sa'd (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Soon after me, people will offer one another condolences on my death." (At that time) the people would ask (in surprise): "What is this?" Then, when the Messenger of Allah (peace and blessings be upon him) passed away, people would meet one another and offer one another condolences and consolation over the great grief of the passing of the Messenger of Allah (peace and blessings be upon him).
This chain is hasan (good).
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب السيرة والمغازي / 4323
Hadith Gradingمحدثین:إسناده حسن
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :قال ابن حجر: هَذَا إِسْنَادٌ حَسَنٌ . » «أخرجه مسند أبي يعلى برقم: 7547، وأخرجه المعجم الكبير للطبراني برقم: 5757»