May the curse of Allah be upon the Jews and the Christians, for they took the graves of their prophets as places of worship - He wanted to warn against what they did. If it were not for that, his grave would be made prominent; yet, he feared it might be taken as a place of worship.
[Al-Bukhari]
Original Hadith
"لَعْنَةُ الله على اليهود والنصارى، اتخذوا قبور أنبيائهم مساجد -يُحَذِّرُ ما صنعوا"". ولولا ذلك أُبْرِزَ قَبْرُهُ، غير أنه خَشِيَ أن يُتَّخَذَ مسجدا.
[صحيح.] - [متفق عليه.]"