Skanda Purana — Vishnu Khanda, Shloka 19
अगस्त्य उवाच । इत्युक्त्वा देवदेवोऽयं ब्रह्मा लोकपितामहः । अन्तर्दधे सुरैः सार्द्धं तीर्थं दृष्ट्वा तपोधन
agastya uvāca | ityuktvā devadevo'yaṃ brahmā lokapitāmahaḥ | antardadhe suraiḥ sārddhaṃ tīrthaṃ dṛṣṭvā tapodhana
阿伽斯提耶说道：“如是言毕，此诸神之神——梵天，诸世之祖父与父——观览圣地（tīrtha）之后，偕同诸天隐没不现，噢，苦行之宝藏者。”
Agastya
Tirtha: Unnamed kuṇḍa/tīrtha in Ayodhyā (contextually the kuṇḍa described next)
Type: kund
Listener: Tapodhana (addressed: 'O treasure of austerity')
Scene: Agastya narrates: Brahmā, surrounded by devas, gazes upon the tīrtha; then Brahmā vanishes (antardhāna) in a burst of subtle light, leaving the sages in reverent stillness.
FAQs
Divine institutions of tīrthas are sanctified by the presence and sanction of the gods, then entrusted to the world for ongoing merit.
The tīrtha just established and praised—Brahmakuṇḍa in Ayodhyā.
No new prescription; it narrates Brahmā’s departure after consecrating the tīrtha.