Al-Matalib al-'Aliyah 3129 — Beneficial counsels

It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that one day the Messenger of Allah (peace and blessings be upon him) came towards the mosque and found some people engaged in conversation with one another whom their talk had made laugh. So he (peace and blessings be upon him) stopped there, greeted them with salam and said: "Remember often the destroyer of pleasures, that is, death." After this incident the Messenger of Allah (peace and blessings be upon him) came out on another occasion and again saw some people talking and laughing, and he said: "Behold! By the One in whose hand is my soul, if you knew the realities that I know, you would laugh little and weep much." The narrator said: The Messenger of Allah (peace and blessings be upon him) came out once again and found people talking and joking, so he (peace and blessings be upon him) greeted them with salam and then said: "Listen! Indeed, Islam began as something strange, and soon it will become strange again just as it began; so glad tidings and Tuba are for those strangers on the Day of Resurrection." It was said to him (peace and blessings be upon him): O Messenger of Allah, who are those strangers? He (peace and blessings be upon him) said: "They are the people who remain firm upon righteousness and goodness at the time when people have fallen into corruption and decay."
Musnad Abi Ya'la: 3129, al-Mu'jam al-Kabir of al-Tabarani: 13093. Its chain contains Kawthar bin Hakim, who is a matruk (abandoned) narrator; however, there are other sahih hadith with this meaning.