Vasiṣṭha's teaching (Mahārāmāyaṇa) 6.28.63

6.28.63

ādatte tittirī mṛdvīṃ tṛṇakoṭimivāmalām .
etadarthamasatye'sminnāsthā kāryā manāgapi .. 63

63. [Sanskrit available] Because he gains after the loss of his gross body, his residence in the transcendental state of Brahma or spiritual existence; as the little bird tittera builds its nest of tender blades, after its grassy habitation is broken down or blown away.

64. [Sanskrit available] Therefore we should never rely in our frail and fragile bodies, but bind our souls to the firm rock of Brahma by the strong rope of our faith, as they bind a bull to the post with a strong cord.