Part 2a.2 - Samadhi will be established by being disciplined and hearing

Moreover:

They should have faith and modesty as well as decency.
With care and pure discipline, they should delight in goodness.
Knowing much and desiring little, they are content.
In such a way, samadhi will quickly be established.

By having faith, it will be established. By having faith in the Dharma, they enter and remain, and excellent faith will therefore increase more and more. The Jewel Heap Sutra says:

For persons who have faith
White dharmas rise by themselves.

With "modesty as well as decency," meditating in samadhi, enthusiastically not giving up, one will produce yogic union. Since, by being careful, the mind is guarded from distraction, samadhi is established. The Sutra on Genuine Samadhi (ting nge ‘dzin dam pa’i mdo) says:

By care, with modesty and decency,
Genuine deep samadhi is established.

Regarding establishing it by discipline, the former text says:

Having discipline and staying with it,
The excellent peace of samadhi is attained.

Rejoicing in virtue, having heard much, having few desires and knowing what is enough we will establish samadhi. The Moon Lamp says:

Desiring a host of excellent qualities, and knowing what is enough,
Having heard much of the Dharma, but reducing personal baggage,
Staying in solitude, rejoicing in being alone,
By this it is not hard to gain this supreme samadhi.