Manava Dharmashastra 4.59

4.59

gāmātmīyāṃ parakīyāṃ vā pibantīṃ apaḥ payo vā na vārayet | na cānyasmai kathayet | prāgdohakālādayaṃ vidhiḥ | dohakāle tu prasravaṇaṃ vihitam | strīliṅganirdeśāt puṃvatsanivāraṇe na niṣedhaḥ | indrāyudhaṃ śakradhanurvijñānacchādyeti yā kāśmīreṣu kathyate | divītyanuvādaḥ | kecittu parvatādisthasya darśane na doṣa ityāhustadarthaṃ divīti |

He shall not prevent a heifer while she is drinking, nor shall he point her out to anybody. Having seen the rainbow in the sky, the wise man shall not show it to any person.—(59)

Medhātithi’s commentary (manubhāṣya):
When a heifer—either his own or some-body’s—is drinking water or milk, he shall not prevent her; nor shall he tell of it to another person.

This rule refers to the time before milking. During milking, it has been enjoined that the flow of milk is to be accelarated (by keeping the calf near, and preventing it from sucking).

The feminine gender (in ‘dhāyantim’) implies that there is no harm in preventing a male calf from sucking.

‘Rainbow’;—that which is called ‘Śakradhanuṣ’ and ‘Vijñanacchāyā’ in Kaśmir. ‘In the sky;’—this is a needless reiteration. But some people have explained that this has been added for the purpose of indicating that there is no harm in seeing and showing the rainbow when it appears over a mountain.—(59)

This verse is quoted in Saṃskāramayūkha (pp. 71 and 68);—and in Nṛsiṃhaprasāda (Saṃskāra, p. 71b).

Comparative notes by various authors
Gautama (9.24-25).—‘When a heifer is drinking, he shall not point her out to another person; nor shall he prevent her.’

Baudhāyana (2.3.32, 33, 38).—‘He shall not tell another person—there is the rainbow;—if he does speak of it, he should call it the jewel-bow; he shall not tell another person of the heifer drinking.’

Āpastamba Dharmasūtra (1.31.9, 10, 16).—‘He shall not point out to another person the cow that may he hankering after something; nor shall he, without sufficient reason, point her out to another person while she is joined by the calf; he shall not tell another person—there is the rainbow.’

Yājñavalkya (1.140.).—‘He shall not point out the drinking heifer; nor shall he enter anywhere except through the proper gate.’

Viṣṇu (71.61-62).—‘He shall not give Information regarding the cow that may be grazing in another man’s field; nor shall he point out the calf that may be drinking milk.’