عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ رَضِيَ اللَّهُ عَنْهُمَا أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ أَفْرَى الْفِرَى مَنِ ادَّعَى غَيْرَ أَبِيهِ وَأَفْرَى الْفِرَى مَنْ أَرَى عَيْنَيْهِ فِي النَّوْمِ مَا لَمْ تَرَيَا وَمَنْ غَيَّرَ تَخُومَ الْأَرْضِ
It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him) said: The greatest lie is to attribute oneself to someone other than one's father; similarly, it is a great lie for a person to describe a dream which he did not see, and for one who alters the signs of the land.