Valmiki Ramayana Bala Kanda Sarga 12 Shloka 8
Original Shlokaमम लालप्यमानस्य पुत्रार्थं नास्ति वै सुखम्। तदर्थं हयमेधेन यक्ष्यामीति मतिर्मम।।1.12.8।।
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पुत्रार्थम् to have sons, लालप्यमानस्य suffering from intense sorrow, मम for me, सुखम् happiness, नास्ति वै not there, तदर्थं for that reason, (अहम् I), हयमेधेन यक्ष्यामि I shall perform HorseSacrifice, इति thus, मम my, मति: intention.
"There is no happiness for me. I am overwhelmed with grief as I have no son. Therefore, I intend to perform a horsesacrifice.