Manava Dharmashastra 2.234

2.234

ādṛtāḥ satkṛtāḥ | ādṛtavacanena pratyupakāraparatvaṃ lakṣyate | yo hyāhato bhavati sa parituṣṭaḥ pratyupakārāya yatate | athavā ādṛtaḥ parituṣṭa ucyate | dharmasya cānantyātparitoṣānupapatteḥ phaladānotsukatvaṃ lakṣyate | sarvāṇi tasya karmāṇdyāśu phaladāyīni bhavanti | yasyaite traya ādṛtāḥ śuśrūṣayā parituṣṭāḥ |
etaistvanārādhitairyatphalakāmena kiñcitkriyate śubhaṃ karma tatsarvaṃ niṣphalam | sarvāḥ kriyāḥ sarvāṇi śrautasmārttāni karmāṇi |
arthavādo'yam | puruṣārtho hyārādhanavidhiḥ | tadatikrame puruṣaḥ pratyavayanmahatā pāpena karmopārjite'pīṣṭaphalabhoge pratibadhyate | ata ucyate sarvāstasyāphalāḥ kriyā iti |

All the duties have been honoured by him who has honoured these three; and all acts remain fruitless for him who does not honour them.—(234).

Medhātithi’s commentary (manubhāṣya):
‘Honoured’—respected. The mention of ‘honouring’ indicates that the person honoured is intent upon repaying the benefits he has received. As a matter of fact, the person who is honoured becomes pleased and tries to repay it. Or, ‘honoured’ may be taken as standing for ‘pleased.’ And as Duties are endless, the entire satisfaction of these would not be possible; so that what is indicated is ‘anxiety to bring about the desired result’; hence what is meant is that ‘all acts done by him bear fruit quickly.’