Valmiki Ramayana Sundara Kanda Sarga 67 Shloka 12

सः he, संस्तरात् from your mat, दर्भम् a blade of grass, गृह्य took out, ब्राह्मेण अस्त्रेण by the mantra of the weapon of Brahma, योजयत् chanted, सः he, दीप्तः blazed, कालाग्निरिव like the fire of the demon's day, द्विजम् bird, अभिमुखः towards the direction, जज्वाल hurled.

'You took out a blade of grass from your mat and chanted the mantra to invoke the weapon of Brahma (Brahmastra) and hurled it on the crow. It blazed like the fire of the doom's day.