Volsunga Saga - Chapter 7
OF THE BIRTH OF SINFJOTLI THE SON OF SIGMUND.
SO on a tide it befell as Signy sat in her bower, that there came to her a witch-wife exceeding cunning, and Signy talked with her in such wise, "Fain am I," says she, "that we should change semblances together."
She says, "Even as thou wilt then."
And so by her wiles she brought it about that they changed semblances, and now the witch-wife sits in Signy's place according to her rede, and goes to bed by the king that night, and he knows not that he has other than Signy beside him.
But the tale tells of Signy, that she fared to the earth- house of her brother, and prayed him give her harbouring for the night; "For I have gone astray abroad in the woods, and know not whither I am going."
So he said she might abide, and that he would not refuse harbour to one lone woman, deeming that she would scarce pay back his good cheer by tale-bearing: so she came into the house, and they sat down to meat, and his eyes were often on her, and a goodly and fair woman she seemed to him; but when they are full, then he says to her, that he is right fain that they should have  but one bed that night; she nowise turned away there- from, and so for three nights together he laid her in bed by him.
Thereafter she fared home, and found the witch-wife, and bade her change semblances again, and she did so.
Now as time wears, Signy brings forth a man-child, who was named Sinfjotli, and when he grew up he was both big and strong, and fair of face, and much like unto the kin of the Volsungs, and he was hardly yet ten winters old when she sent him to Sigmund's earth-house; but this trial she had made of her other sons or ever she had sent them to Sigmund, that she had sewed gloves on to their hands through flesh and skin, and they had borne it ill and cried out thereat; and this she now did to Sinfjotli, and he changed 'countenance in nowise thereat. Then she flayed off the kirtle so that the skin came off with the sleeves, and said that this would be torment enough for him; but he said —
"Full little would Volsung have felt such a smart as this."
So the lad came to Sigmund, and Sigmund bade him knead their meal up, while he goes to fetch firing; so he gave him the meal-sack, and then went after the wood, and by then he came back had Sinfjotli made an end of his baking. Then asked Sigmund if he had found nothing in the meal.
"I misdoubted me that there .was something quick in the meal when I first fell to kneading of it, but I have kneaded it all up together, both the meal and that which was therein, whatsoever it was." Then Sigmund laughed out, and said —
 "Naught wilt thou eat of this bread to-night, for the most deadly of worms hast thou kneaded up therewith."
Now Sigmund was so mighty a man that he might eat venom and have no hurt therefrom; but Sinfjotli might abide whatso venom came on the outside of him, but might neither eat nor drink thereof.