Anas bin Malik narrated that a man among his companions was dying so he said- meaning a man said to him:

"Glad tidings of Paradise." To which the Messenger of Allah (ﷺ) said: "You do not know. Perhaps he spoke of what did not concern him or he was greedy with that which would not decrease him."

حَدَّثَنَا سُلَيْمَانُ بْنُ عَبْدِ الْجَبَّارِ الْبَغْدَادِيُّ، حَدَّثَنَاَ عُمَرُ بْنُ حَفْصِ بْنِ غِيَاثٍ، حَدَّثَنَا أَبِي، عَنِ الأَعْمَشِ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ تُوُفِّيَ رَجُلٌ مِنْ أَصْحَابِهِ فَقَالَ يَعْنِي رَجُلٌ أَبْشِرْ بِالْجَنَّةِ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏

‏ أَوَلاَ تَدْرِي فَلَعَلَّهُ تَكَلَّمَ فِيمَا لاَ يَعْنِيهِ أَوْ بَخِلَ بِمَا لاَ يَنْقُصُهُ ‏

‏ ‏.‏ قَالَ هَذَا حَدِيثٌ غَرِيبٌ ‏.‏