Bhagavad Gita · 2.3

क्लैब्यं मा स्म गमः पार्थ नैतत्त्वय्युपपद्यते।क्षुद्रं हृदयदौर्बल्यं त्यक्त्वोत्तिष्ठ परन्तप॥

klaibyaṁ mā sma gamaḥ pārtha naitat tvayy upapadyate kṣhudraṁ hṛdaya-daurbalyaṁ tyaktvottiṣhṭha parantapa

Do not yield to unmanliness, O Partha. It does not befit you. Cast off this petty weakness of heart and arise, O scorcher of enemies!

— Bhagavad Gita 2.3

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)