The Law Code of Yājñavalkya 3.3.5

3.3.5

ayaṃ ca putreṣu patnīniḥkṣepo vidyamānabhāryasya mṛtabhāryasyāpy āpastambādibhiḥ vanavāsasmaraṇāt (ĀpDh 2.22.6–24)| ato yat dāhayitvāgnihotreṇa (YDh 1.89) iti punarādhānavidhānaṃ, tad aparipakvakaṣāyaviṣayam | sāgniḥ sopāsanaḥ (YDh 3.45) ity atrāpi yadārdhādhānaṃ kṛtaṃ tadā śrautāgnibhir gṛhyeṇa ca sahito vanaṃ vrajet | sarvādhāne tu śrautair eva kevalam | yadi kathaṃcij jyeṣṭhabhrātur anāhitāgnitvādinā śrautāgnayo 'nāhitās tarhi kevalaṃ sopāsano vrajed ity evaṃ vivecanīyam | agninayanaṃ ca tannivartyāgnihotrādikarmasiddhyartham | ata eva manuḥ |

And this entrustment of the wife to the sons applies to one who has a living wife, because the dwelling in the forest is taught by Āpastamba and others even for one whose wife has died. Therefore, the rule for re-establishing the sacred fires, stated in "Having cremated her with the agnihotra fires," pertains to one whose worldly passions are not yet mature [for renunciation]. As for the phrase "keeping his sacred fires, and keeping his domestic fire": when the partial establishment of sacred fires was performed, he should go to the forest accompanied by the solemn Vedic fires and by the domestic fire. But in the case of the full establishment of fires, [he goes] solely with the solemn fires. If somehow the solemn fires were not established because of the elder brother's not having established sacred fires or the like, then he should go solely keeping the domestic fire—thus it should be understood. And the taking along of the fires is for the accomplishment of the rites of the agnihotra and so forth to be performed by them. For this very reason, Manu [says]: