Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 23: The History of Kāmāśrama
Text 1.23.20

सत्कारं समनुप्राप्य कथाभिरभिरञ्जयन्।
यथार्हमजपन्सन्ध्यामृषयस्ते समाहिताः॥

satkāraṁ samanuprāpya kathābhir abhirañjayan
yathārham
ajapan sandhyām ṛṣayas te samāhitāḥ

satkāram samanuprāpya = they honored Viśvāmitra by asking about his welfare and so on; kathābhiḥ = with various talks; abhirañjayan = and entertained the guests; yathā-arham = according to their capacity; ajapan = chanted the gāyatrī-mantra; sandhyām = when dusk arrived; ṛṣayaḥ = the sages; te = Viśvāmitra and others; samāhitāḥ = attentively.

They honored Viśvāmitra by asking about his welfare and so on, and entertained the guests with various talks. When dusk arrived, the sages, Viśvāmitra and others attentively chanted their gāyatrī-mantra according to their capacity.

One can chant the gāyatrī a thousand times, or a hundred times or ten times.1[7]

[7] sahasra-paramāṁ devīṁ śata-madhyamāṁ daśāvarām.

1 This refers to the brahma-gāyatrī. Of course, all this should be done as directed by the bona fide spiritual master.