SB 10.69.25
kvapi sandhyam upasinam
japantam brahma vag-yatam
ekatra casi-carmabhyam
carantam asi-vartmasu
Translation:
Somewhere Lord Krsna was observing the rituals for worship at sunset by refraining from speech and quietly chanting the Gayatri mantra, and elsewhere He was moving about with sword and shield in the areas set aside for sword practice.
Purport:
According to Srila Visvanatha Cakravarti, the words sandhyam upasinam indicate sunset rituals, whereas the words asi-carmabhyam carantam refer to sword practice, which takes place at dawn.