Reference for Niddah 141:2

אמרו

at the time of marital intercourse. Did not many, they said to him, act in this manner but it did not avail them? — Rather, let him pray for mercy from Him to whom are the children, for it is said, Lo, children are a heritage of the Lord; the fruit of the womb is a reward.<span class="x" onmousemove="('comment',' Ps. CXXVII, 3. ');">²</span>

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