I believe you heard that Abu ‘Ubaydah has returned from Bahrain with something
Authentic hadithعن عمرو بن عوف الأنصاري رضي الله عنه أن رسول الله صلى الله عليه وسلم بعث أبا عبيدة بن الجراح رضي الله عنه إلى البحرين يأتي بِجِزْيَتِهَا، فَقدِم بمالٍ من البحرين، فسمعت الأنصار بقدوم أبي عبيدة، فَوَافَوْا صلاة الفجر مع رسول الله صلى الله عليه وسلم فلما صلى رسول الله صلى الله عليه وسلم انصرف، فَتَعَرَّضُوا له، فتَبسَّم رسول الله صلى الله عليه وسلم حين رآهم، ثم قال: «أَظُنُّكُمْ سَمِعتم أن أبا عبيدة قَدِم بشيءٍ من البحرين؟» فقالوا: أجل، يا رسول الله، فقال: «أبشروا وأمِّلوا ما يَسُرُّكُم، فوالله ما الفَقرَ أخشى عليكم، ولكني أخَشى أن تُبْسَط الدنيا عليكم كما بُسِطَت على من كان قبلكم، فتَنَافسوها كما تَنَافسوها، فَتُهْلِكَكُم كما أهْلَكَتْهُمْ».
‘Amr ibn ‘Awf al-Ansāri (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) sent Abu ‘Ubaydah ibn al-Jarrāh to Bahrain to collect the Jizyah (yearly tax), and he returned from Bahrain with money. The Ansār heard the news of Abu ‘Ubaydah's return and they gathered for the Fajr prayer with the Messenger of Allah (may Allah's peace and blessings be upon him). After he had prayed and left, the Ansār presented themselves before him. When he saw them, he smiled and said: "I believe you heard that Abu ‘Ubaydah has returned from Bahrain with something." They replied: "Yes, O Messenger of Allah." The Prophet (may Allah's peace and blessings be upon him) said: "Rejoice, and hope for that which will please you. By Allah, it is not poverty that I fear for you. What I fear for you is that the world expands (with lots of wealth) for you just as it did for the people before you. Then you will compete as they competed, then it will destroy you just as it destroyed them."
Explanation
The Prophet (may Allah's peace and blessings be upon him) sent Abu ‘Ubaydah (may Allah be pleased with him) to Bahrain to collect the tax from them. When he returned to Madīnah and the Ansār heard about his return, they went to the Prophet and gathered waiting for him at the Fajr prayer. After the Prophet prayed and started to leave, the Ansār presented themselves to him and he smiled because he knew they wanted some of the money. He said to them: "Perhaps you've heard that Abu ‘Ubaydah has returned?" They said: "Yes, O Messenger of Allah," meaning we have come to receive our share of the money. So the Prophet gave them glad tidings that made them happy. He informed them that he does not fear poverty for them, because most of the time the impoverished person is closer to the truth than the wealthy one. Rather, he feared for them that the pleasures of the worldly life would be given to them, and then they would compete among themselves to attain them. A person in such a state (of competition) is never satisfied with what he has and he always wants more and more by any means. He does not care whether he acquires it through lawful or unlawful means. There is no doubt that this is a type of dispraised competition which attaches the person to this world and distances him from the Hereafter (and remembrance of it). So, as a result, the person is destroyed just as the previous nations were destroyed for the same reason.
Source · Narrated by Bukhari & Muslim
From the Hadith Encyclopedia (hadeethenc.com).