Rāhula

(DPPN: The only son of Gotama Buddha. He was born on the day on which has father left the household life. [Gotama left the household life on the day he was born. The birth of his son was a large factor in his decision to leave.] When the Buddha visited Kapilavatthu for the first time after his Enlightenment ... Rāhula's mother sent the boy to the Buddha to ask for his inheritance. The Buddha gave him no answer, and, at the conclusion of the meal, left the palace. Rāhula followed him, reiterating his request, until at last the Buddha asked Sāriputta to ordain him ... the Buddha preached to him constantly many suttas for his guidance.

This fragment, on lying, is from one, when Rāhula was age 14, having been an initiated Beggar for seven years: From: PTS, Horner, Trans., The Middle Length Sayings, II, pp87 [NOTE: I find this sutta particularly poorly translated, and have taken liberties with it to make it make sense.]:

Discourse on An Exhortation to Rāhula at Ambalatthika

I hear tell, once upon a time the Lucky Man, Rajagaha, Bamboo Grove, Squirrels Feeding Ground, came a Revisiting. At that time the venerable Rāhula was staying at Ambalatthika. Then the Lucky Man, emerging from solitary meditation towards evening, approached Ambalatthika and the venerable Rāhula. Then the venerable Rāhula saw the Lucky Man coming in the distance; seeing him, he made ready a seat and water for washing the feet. The Lucky Man sat down on the seat made ready and bathed his feet. The venerable Rāhula, having greeted the Lucky Man, sat down at a respectful distance.

Then the Lucky Man, having washed his feet, left the small amount of water that remained in the water-vessel. He then addressed the venerable Rāhula, saying: "Do you, Rāhula, see this small amount of water that remains in the water-vessel?"

"Yes, revered sir."

"Even so, Rāhula, amounting to little is the recluseship of those who have no shame at intentional lying." Then the Lucky Man, having thrown away that small amount of water, addressed the venerable Rāhula, saying: "Do you, Rāhula, see this water that has been thrown away?"

"Yes,. Revered sir."

"Even so, Rāhula, thrown away is the recluseship of those who have no shame at intentional lying." Then the Lucky Man, having turned upside down that water-vessel, addressed the venerable Rāhula, saying: "Do you, Rāhula, see this water-vessel that has been turned upside down?"

"Yes, revered sir."
"Even so, Rāhula, turned upside down is the recluseship of those who have no shame at intentional lying." Then the Lucky Man, having turned upright that water-vessel, addressed the venerable Rāhula, saying: "Do you, Rāhula, see this empty water-vessel?"

"Yes, revered sir."

"Even so, Rāhula, empty is the recluseship of those who have no shame at intentional lying.

Rāhula, it is like a king's bull-elephant whose tusks are as long as a plough-pole, massive, finely bred, whose home is the battle-field, and who, when going forth to battle, uses his forelegs, uses his hind legs, uses the forepart of his body, uses the hind part of his body, uses his head, uses his ears, uses his tusks and uses his tail, protecting only his trunk.

Thereupon it occurs to the mahout: 'This king's bull-elephant whose tusks are as long as a plough-pole ... protects his trunk. This king's bull-elephant has not thrown away his life.'

But when, Rāhula, the king's bull-elephant whose tusks are as long as a plough pole ... uses his forelegs ... uses his tail and uses his trunk, it thereupon occurs to the mahout: 'This king's bull-elephant ... uses his tail and uses his trunk. This king's bull-elephant has thrown away his life, there is nothing the king's bull elephant will not do.' [As is often the case in the suttas, this same exact simile is used in a positive way elsewhere to show absolute dedication.]

Even so, Rāhula, of anyone for whom there is no shame at intentional lying, of him I say that there is no evil he will not do [This is arrived at this way: A man might steal from hunger, or kill in self defense or in an uncharacteristic fit of rage, but for the liar there is no real world and he sees no self interest in ethical conduct]. Wherefore, Rāhula, train yourself this way: 'I will not intentionally speak a lie, even for fun' — this is how you must train yourself, Rāhula.

From the Psalms

Twice blest of fortune am I whom my friends
Call 'Lucky Rāhula.' For I am both
Child of the Buddha and a Seer of truths;
Yea, and intoxicants are purged from me;
Yea, and there's no more coming back to be.
Ar'hant am I, worthy men's offerings;
'Thrice skilled' my ken is of ambrosial things.
Blinded are beings by their sense-desires,
Spread o'er them like a net; covered are they
By cloak of craving; by their heedless ways
Caught as a fish in mouth of funnel-net,
But I, that call of sense abandoning,
Have cut and snapped the bonds of devil's lure.
Craving with craving's root abolishing;
Cool am I now; extinct is fever's fire.

References:

see: SN: Rāhula Samyutta iii, SN 3.22.91, SN 3.22.92, AN 1.209