येन च्छन्दसा स्तोष्यन्स्यात्तच्छन्द उपधावेद्येन स्तोमेन स्तोष्यमाणः स्यात्तंस्तोममुपधावेत् ॥ १.३.१० ॥
yena cchandasā stoṣyansyāttacchanda upadhāvedyena stomena stoṣyamāṇaḥ syāttaṃstomamupadhāvet || 1.3.10 ||
10. One may use the Gāyatrī or some other hymn when praying, but one should meditate on it. Again, one may use a number of Sāma mantras while praying, but one must meditate on them [along with the deities to whom they are addressed].
Yena chandasā, by the Gāyatrī or whatever other hymn; stoṣyan syāt, one is going to pray; tat chandaḥ upadhāvet, one should meditate on that hymn; yena stomena stoṣyamāṇaḥ syāt, the group of Sāmas by which a person is going to pray; tam stomam upadhāvet, one should meditate on those Sāmas [along with the deities to whom they are addressed].
Whether you use the Gāyatrī or some other hymn while praying, you should not forget to meditate on that hymn. In fact, whatever mantras you use, you should meditate on them as well as on the deities to whom they are directed.