The Mahabharata by Krishna Dwaipayana Vyasa.
Book 1, Adi Parva, Section 130th.
Sambhava Parva continued.
"Janamejaya said, 'O Brahmana, it behoveth
thee to relate to me everything about the
birth of Kripa.
How did he spring from a clump of heath?
Whence also did he obtain his weapons?'
"Vaisampayana said, 'O king, the great sage
Gautama had a son named Saradwat.
This Saradwat was born with arrows (in hand).
O oppressor of foes, the son of Gautama exhibited
great aptitude for the study of the science
of weapons, but none for the other sciences.
Saradwat acquired all his weapons by those
austerities by which Brahmanas in student
life acquire the knowledge of Vedas.
Gautama (the son of Gotama) by his aptitude
for the science of weapons and by his austerities
made Indra himself greatly afraid of him.
Then, O thou of Kuru's race, the chief of
the gods summoned a celestial damsel named
Janapadi and sent her unto Gautama, saying,
'Do thy best to disturb the austerities of
Gautama.'
Repairing unto the charming asylum of Saradwat,
the damsel began to tempt the ascetic equipped
with bow and arrows.
Beholding that Apsara, of figure unrivalled
on earth for beauty, alone in those woods
and clad in a single piece of cloth, Saradwat's
eyes expanded with delight.
At the sight of the damsel, his bow and arrows
slipped from his hand and his frame shook
all over with emotion; but possessed of ascetic
fortitude and strength of soul, the sage mustered
sufficient patience to bear up against the
temptation.
The suddenness, however, of his mental agitation,
caused an unconscious emission of his vital
fluid.
Leaving his bow and arrows and deer-skin behind,
he went away, flying from the Apsara.
His vital fluid, however, having fallen upon
a clump of heath, was divided into two parts,
whence sprang two children that were twins.
"And it happened that a soldier in attendance
upon king Santanu while the monarch was out
a-hunting in the woods, came upon the twins.
And seeing the bow and arrows and deer-skin
on the ground, he thought they might be the
offspring of some Brahmana proficient in the
science of arms.
Deciding thus, he took up the children along
with the bow and arrows, and showed what he
had to the king.
Beholding them the king was moved with pity,
and saying, 'Let these become my children,'
brought them to his palace.
Then that first of men, Santanu, the son of
Pratipa having brought Gautama's twins into
his house, performed in respect of them the
usual rites of religion.
And he began to bring them up and called them
Kripa and Kripi, in allusion to the fact that
he brought them up from motives of pity (Kripa).
The son of Gotama having left his former asylum,
continued his study of the science of arms
in right earnest.
By his spiritual insight he learnt that his
son and daughter were in the palace of Santanu.
He thereupon went to the monarch and represented
everything about his lineage.
He then taught Kripa the four branches of
the science of arms, and various other branches
of knowledge, including all their mysteries
and recondite details.
In a short time Kripa became an eminent professor
of the science (of arms).
And the hundred sons of Dhritarashtra, and
the Pandavas along with the Yadavas, and the
Vrishnis, and many other princes from various
lands, began to receive lessons from him in
that science.'" ...
