It is a Sunnah to visit graves as they remind one of death

The Messenger of Allah ﷺ as saying: I forbade you to visit graves, but you may now visit them, for in visiting them there is a reminder (of death).  

قَالَ رَسُولُ اللَّهِ ﷺ نَهَيْتُكُمْ عَنْ زِيَارَةِ الْقُبُورِ فَزُورُوهَا فَإِنَّ فِي زِيَارَتِهَا تَذْكِرَةً  

[Machine] The Messenger of Allah ﷺ said: "I used to forbid you from visiting graves, but now visit them and do not say anything that would drive them away."  

قَالَ رَسُولُ اللهِ ﷺ كُنْتُ نَهَيْتُكُمْ عَنْ زِيَارَةِ الْقُبُورِ فَزُورُوهَا وَلَا تَقُولُوا هُجْرًا  

The Messenger of Allah ﷺ as saying: I forbade you to visit graves, but you may now visit them, for in visiting them there is a reminder (of death). (Using translation from Abū Dāʾūd 3235)   

قَالَ رَسُولُ اللَّهِ ﷺ «نَهَيْتُكُمْ عَنْ زِيَارَةِ الْقُبُورِ فَزُورُوهَا فَإِنَّهَا تُذَكِّرُكُمُ الْمَوْتُ»  

[Machine] The Messenger of Allah ﷺ said, "I have forbidden you from visiting graves, but now go and visit them, for there are lessons to be learned from them."  

قَالَ رَسُولُ اللهِ ﷺ «نَهَيْتُكُمْ عَنْ زِيَارَةِ الْقُبُورِ فَزُورُوهَا فَإِنَّ لَكُمْ فِيهَا عِبْرَةً»  

"نَهَيتُكُمْ عَنْ زِيَارَةِ الْقُبُورِ فَزُورُوهَا، فَإنَّهَا تُذَكِّرُكُمُ الْمَوْتَ".