The Gesta Danorum (Books I-IX) on Feng
The Danish History, > Book Three.
attestation: Feng murdered his brother Horwendil out of jealousy and married Gerutha, capping fratricide with incest
"he resolved treacherously to waylay his brother, thus showing that goodness is not safe even from those of a man's own house"
attribution: Feng justified the murder by claiming Horwendil had treated the gentle Gerutha with extreme hatred
"Gerutha, said he, though so gentle that she would do no man the slightest hurt, had been visited with her husband's extremest hate; and it was all to save her that he had slain his brother"
attestation: A friend of Feng devised a plan to hide an eavesdropper in Gerutha's chamber to overhear Amleth's private speech with his mother
"Amleth should be closeted alone with his mother in her chamber; but a man should first be commissioned to place himself in a concealed part of the room and listen heedfully"
attestation: Feng sent Amleth to the King of Britain with a wooden letter ordering his execution, fearing to kill him openly due to Rorik's displeasure
"Feng now suspected that his stepson was certainly full of guile, and desired to make away with him, but durst not do the deed for fear of the displeasure, not only of Amleth's grandsire Rorik"
attestation: Feng leapt from his couch and was cut down, unable to draw the strange sword, completing Amleth's revenge for his father's murder
"Feng, on hearing this, leapt from his couch, but was cut down while deprived of his own sword, and as he strove in vain to draw the strange one"