Valmiki Ramayana Sundara Kanda Sarga 28 Shloka 18
Original Shlokaसा शोकतप्ता बहुधा विचिन्त्य सीताऽथ वेण्युद्ग्रथनं गृहीत्वा। उद्बुध्य वेण्युद्ग्रथनेन शीघ्रमहं गमिष्यामि यमस्य मूलम्।।5.28.18।।
1 source checked for this shloka
शोकाभितप्ता burning with grief, सीता Sita, बहुधा in many ways, विचिन्त्य after worrying, अथ then, वेण्युद्ग्रथनम् braid of her hair, गृहीत्वा holding, अहम् I, वेण्युद्ग्रथनेन by the braid, उद्बुध्य tie, शीघ्रम् quickly, यमस्य lord of death's, मूलम् presence, गमिष्यामि I will reach.
"Burning in grief, worrying in many ways, Sita took hold of her braid and said", by tying myself with this braid I shall quickly reach the presence of the lord of death".