classic waka stream

巣守にとおもふ心はとどむれど
かひあるべくもなしとこそ聞け
Roma-ji

Sumori ni to omou kokoro wa todomuredo kai arubeku mo nashi to koso kike

English Translation
The wish to stay on
as that unhatched egg — my heart
I leave here with you
But I am told there would be
no use, no life, in staying
Meaning
The wish to stay on as that unhatched egg — that much of my heart I leave here. But I am told there would be no use in it, no life in the shell.
Commentary
94 The Egg Left in the Nest

After the death of the wife of the late Prince of the Ministry of Central Affairs, he had been living with his young children at the house of her father, the Minister of the Right of Sanjō. When the mourning was over, since he could not go on alone indefinitely, he thought of taking as his wife the Ninth Lady, the dead woman's younger sister, and her parents and brothers saw no objection. But then, somehow, word got about that Morotada, while still a chamberlain, had been sending letters to the Ninth Lady. Displeased, it seems, the prince went back to his own house; and at that the Lady of Sanjō sent him "Naki hito no sumori ni dani mo narubeki o ima wa to kaeru kyō no kanashisa", to which his reply was "Sumori ni to omou kokoro wa todomuredo kai arubeku mo nashi to koso kike". That is the whole of the section.
The Prince of the Ministry of Central Affairs headed that ministry. The Minister of the Right of Sanjō is Fujiwara no Sadakata, who appears in the ninety-first section; the dead wife was his daughter and the Ninth Lady her younger sister. The Lady of Sanjō was also Sadakata's daughter, and appears in the ninety-fifth and ninety-sixth sections. A chamberlain served close to the emperor's person.
The setting is the same day of his departure.
What prompted his poem is hers, "Naki hito no sumori ni dani mo narubeki o ima wa to kaeru kyō no kanashisa", asking him to stay.
This reply closes the ninety-fourth section. The prose passes no judgement; the section consists of the exchange alone.

He takes her word for the unhatched egg over whole, starting his poem from hers.
What follows is that he leaves that much of his heart behind: the wish itself stays in the house.
The word in the fourth line means both an egg and any use or purpose. Behind it lies the fact that an egg left in the nest will not hatch however long it is sat on, so that staying to no purpose and a shell with nothing in it are one phrase. Where the same word was a shell in the ninety-third section, here it is an egg.
The closing is in the grammar of report, with an emphatic particle governing the verb: so he is told. Without naming it, he points at the rumour of another man's letters to the Ninth Lady.
Source
Yamato Monogatari
Other