Valmiki Ramayana Ayodhya Kanda Sarga 20 Shloka 49

प्रावृषि in rainy season, नवाम्भसा with fresh water, स्पृष्टम् contacted, महानद्याः mighty river's, कूलम् इव like bank, मम my, इदम् this, हृदयम् heart, यत् for which reason, न दीर्यते does not break, स्थिरम् firm (hard), मन्ये am thinking.

I think my heart must be very firm (hard) like the bark of a great river which, touched by (a flood of) fresh water in the rainy season does not disintegrate.