Rabbi Yochanan said:--If, after the death of her husband, a woman should
remain unmarried for ten years and then marry again, she will have no
children. Rav Nachman added:--Provided she have not thought of marrying
all the while; but if she had thought of marrying again, in that case
she will have children. Rava once said to Rav Chisda's daughter (who
bore children to Rava, though she did not marry him until ten years
after her first husband's death), "The Rabbis have their doubts about
you." She replied, "I had always set my heart upon thee." A woman once
said to Rav Yoseph, "I waited ten years before I married again, and then
I had children." "Daughter," said he, "do not bring the words of the
wise into discredit. It is thou, not they, that are mistaken." Then the
woman confessed that she had been a transgressor.
THE TALMUD, _Yevamoth_, fol. 34, col. 2.