1On one occasion the Blessed One was dwelling at Sāvatthī. … There the Blessed One addressed the Venerable Sāriputta thus: "Sāriputta, in ‘The Questions of Ajita’ of the Parayana it is said: [n.87] The Parayana, the "Going to the Far Shore," is the last chapter of Sn. It consists of sixteen sections (plus prologue and epilogue), in each of which the Buddha replies to questions posed by one of sixteen brahmin students. "The Questions of Ajita" is the first of the sixteen sections.

2‘Those who have comprehended the Dhamma,
And the manifold trainees here:
Asked about their way of conduct,
Being discreet, tell me, dear sir.’ [n.88] Spk-pṭ: Those who have comprehended the Dhamma (saṅkhātadhamma) are the arahants, who have penetrated the (four) truths. The trainees (sekha) are the seven types of persons—those on the four paths and the lower three fruits.
Saṅkhātadhammā could be understood to mean either "those who have comprehended the Dhamma," i.e., the teaching, or "those who have comprehended things," i.e., phenomena and their principles. Nidd II 34–35 (Be) glosses in both ways: as those who have known the Dhamma (ñātadhamma), by knowing all formations as impermanent, etc.; and as those who have comprehended the aggregates, elements, sense bases, etc. The trainees (sekhā) are so called because they train in the higher virtue, the higher mind (the jhānas), and the higher wisdom. Though Norman says that Pj II and Nidd II do not take sekhā and puthū as going together (GD, p. 367, n. to 1038), read correctly both these texts do place the two words in apposition. The trainees are manifold (puthū) because they fall into the seven types.

3How should the meaning of this, stated in brief, be understood in detail?"

When this was said, the Venerable Sāriputta was silent.

4A second time and a third time the Blessed One addressed the Venerable Sāriputta thus: "Sāriputta, in ‘The Questions of Ajita’ in the Parayana it is said … sn.ii.48

5‘Those who have comprehended the Dhamma,
And the manifold trainees here:
Asked about their way of conduct,
Being discreet, tell me, dear sir.’

6How should the meaning of this, stated in brief, be understood in detail?"

When this was said, a second time and a third time the Venerable Sāriputta was silent. [n.89] Spk: Why did he remain silent up to the third time? He was not puzzled by the question but by the Buddha’s intention (ajjhāsaya). For it was possible to answer in many ways—by way of the aggregates, elements, sense bases, or conditionality—and he wanted to catch the Teacher’s intention. Then the Teacher, aware of the reason for his silence, gave him the method with the words: “Do you see...?”

7"Sāriputta, do you see: ‘This has come to be’? Sāriputta, do you see: ‘This has come to be’?"

"Venerable sir, one sees as it really is with correct wisdom: ‘This has come to be.’ Having seen as it really is with correct wisdom: ‘This has come to be,’ one is practising for the purpose of revulsion towards what has come to be, for its fading away and cessation. [n.90] Spk: This has come to be (bhūtam idaṁ): this is said of the five aggregates. Thus the Teacher gave the elder the method, implying, "Answer my question by way of the five aggregates." Then, just as the great ocean appears as one open expanse to a man standing on the shore, so as soon as he was given the method the answer to the question appeared to the elder with a hundred and a thousand methods. With correct wisdom (sammā paññāya): one sees it with path-wisdom together with insight. One is practising: from the stage of virtue as far as the path of arahantship one is said to be practising for the purpose of revulsion, etc. This section shows the practice of the trainee.

One sees as it really is with correct wisdom: ‘Its origination occurs with that as nutriment.’ [n.91] Tadāhārasambhavaṁ. On nutriment see SN12.11, 12and n. 18 above. No doubt it is the dependence of the five aggregates on nutriment that accounts for the inclusion of this sutta in the Nidanasaṁyutta. A similar treatment of nutriment, in catechism form, is at MN I 260,7–32.
Spk resolves tadāhārasambhavaṁ as taṁ āhārasambhavaṁ, apparently taking tad to represent the five aggregates. I see the whole expression as qualifying an implicit subject ("its") and take tad ("that") as a specification of āhāra. Such an interpretation seems required by the parallel statement on cessation. See too the use of the expression tadāhāra at SN II 85,6, 86,12, 87,6, etc., which supports this interpretation. Having seen as it really is with correct wisdom: ‘Its origination occurs with that as nutriment, ’ one is practising for the purpose of revulsion towards its origination through nutriment, for its fading away and cessation.

One sees as it really is with correct wisdom: ‘With the cessation of that nutriment, what has come to be is subject to cessation.’ Having seen as it really is with correct wisdom: ‘With the cessation of that nutriment, what has come to be is subject to cessation, ’ one is practising for the purpose of revulsion towards what is subject to cessation, for its fading away and cessation.

It is in such a way that one is a trainee.

8"And how, venerable sir, has one comprehended the Dhamma? Venerable sir, one sees as it really is with correct wisdom: ‘This has come to be.’ Having seen as it really is with correct wisdom: ‘This has come to be,’ through revulsion towards what has come to be, through its fading away and cessation, one is liberated by nonclinging.

One sees as it really is with correct wisdom: ‘Its origination occurs with that as nutriment.’ Having seen as it really is with correct wisdom: ‘Its origination occurs with that as nutriment,’ through revulsion towards its origination through nutriment, through its fading away and cessation, one is liberated by nonclinging.

One sees as it really is with correct wisdom: ‘With the cessation of that nutriment, what has come to be is subject to cessation.’ Having seen as it really is with correct wisdom: ‘With the cessation of that nutriment, what has come to be is subject to cessation,’ through revulsion towards what is subject to cessation, through its fading away sn.ii.49 and cessation, one is liberated by nonclinging. [n.921] Anupādā vimutto. Spk: One is liberated by not grasping anything at all with the four kinds of clinging (upādāna). This section shows the arahant.

It is in such a way that one has comprehended the Dhamma.

"Thus, venerable sir, when it is said in ‘The Questions of Ajita’ of the Parayana:

9‘Those who have comprehended the Dhamma,
And the manifold trainees here:
Asked about their way of conduct,
Being discreet, tell me, dear sir.’—

10it is in such a way that I understand in detail the meaning of this that was stated in brief."

11–13"Good, good, Sāriputta! … the Buddha repeats here the entire statement of the Venerable Sāriputta sn.ii.50

14It is in such a way that the meaning of this, stated in brief, should be understood in detail."