Ta'anis 11a - Marital Relations During Famine

2 points:

1. The gemara cites a braisa that one who has no children is permitted to have relations in a year of a famine. What is the source of this Heter? Perhaps it can be explained based on Rashash and Gevuras Ari who understand this to refer to anyone who did not fulfill 'Pru u'rvu', even if they have a child. The heter may be that the mitzvah aseh of 'pru u'rvu' pushes off the issur of having relations. However, this would be dependent on various answers of Tosafos Baba Basra 13a whether or not this would qualify as violating the issur at the same time as performing the mitzvah.

2. The maharsha (agados) explains Tosafos that both Yosef and Levi had not performed 'pru u'rvu' so it was mutar for them to have relations during the famine. Yosef refrained as a middas chassidus, Levi did not, but we can deduce that since it is a midas chassidus if one does not have children, it would be an issur for one who already fulfilled the mitzvah (as the gemara implies "assur"). The question is: There should be no place for middas chasidus. If one has not fulfilled the mitzvah, it should be assur to be mevatel the mitzvah and should be required to have relations in order to perform the mitzvah! This would indicate that delaying the mitzvah of 'pru u'rvu' until after the famine would not be considered a bitul mitzvah and it would therefore be a middas chassidus to abstain.