Matsyapurana 7.55

7.55

vajreṇa saptadhā cakre taṃ garbhaṃ tridaśādhipaḥ
tataḥ saptaiva te jātāḥ kumārāḥ sūryavarcasaḥ //

Diti, not knowing the foul intentions of Indra, did not entertain any suspicion, and she went on following the injunctions of her husband very closely, till there remained only three days to complete the century. She was so much surcharged with joy that she failed to observe the precautions, and one day she did not wash her feet, kept her hair unkempt and went to sleep like that.—52-53. In her recklessness, she slept in course of the day, with her head towards the north. All those irregularities afforded a good opportunity to Indra to enter into her womb in His subtle body; and by His weapon divided the child in the womb into seven parts. To His great surprise and dismay each part developed into a child. They all began to cry in the womb, then Indra divided each one into seven parts. Indra thus divided the child in the womb into fortynine parts, but each part became a child, and they all began to cry. On seeing this, He was awfully astonished, and asked them not to cry.—54--58.