The Prophet ﷺ said, "Do not abuse the dead, for they have reached the result of what they have done." (Using translation from Bukhārī 6516)  

قَالَ رَسُولُ اللهِ ﷺ «لَا تَسُبُّوا الْأَمْوَاتَ فَإِنَّهُمْ قَدِ أَفْضَوْا إِلَى مَا قَدَّمُوا»  

"I heard Anas bin Malik say: The Messenger of Allah said: 'The dead person is followed by three: His family, his wealth and his deeds. Then two of them come back: His family and his wealth, and there remain only his deeds."' (Using translation from Nasāʾī 1937)  

قَالَ رَسُولُ اللهِ ﷺ «يَتْبَعُ الْمَيِّتُ ثَلَاثَةٌ أَهْلُهُ وَمَالُهُ وَعَمَلُهُ فَيَرْجِعُ اثْنَانِ أَهْلُهُ وَمَالُهُ وَيَبْقَى وَاحِدٌ وَهُوَ عَمَلُهُ»  

"The believer owes six duties toward his fellow believer: To visit him when he is sick, to attend his funeral when he dies, to accept his invitation, to greet him with Salam when he meets him, to reply to him (say: Yarhamuk Allah, may Allah have mercy on you) when he sneezes and to be sincere to him, whether he is absent or present." (Hasan). (Using translation from Nasāʾī 1938)  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ «لِلْمُؤْمِنِ عَلَى الْمُؤْمِنِ سِتُّ خِصَالٍ يَعُودُهُ إِذَا مَرِضَ وَيَشْهَدُهُ إِذَا مَاتَ وَيُجِيبُهُ إِذَا دَعَاهُ وَيُسَلِّمُ عَلَيْهِ إِذَا لَقِيَهُ وَيُشَمِّتُهُ إِذَا عَطَسَ وَيَنْصَحُ لَهُ إِذَا غَابَ أَوْ شَهِدَ»