Hadith 7.57

7.56:
Narrated Zainab bint Salama: Um Habiba said to Allah's Apostle
"We have heard that you want to marry Durra bint Abu−Salama."
Allah's Apostle said, "Can she be married along with Um Salama
(her mother)? Even if I have not married Um Salama, she would
not be lawful for me to marry, for her father is my foster
brother." 'And there is no blame on you if you make hint of
betrothal or conceal it in your hearts. Allah is
Oft−Forgiving, Most Forbearing.' (2.235) Ibn `Abbas said,
"Hint your intention of marrying' is made by saying (to the
widow) for example: "I want to marry, and I wish that Allah
will make a righteous lady available for me.' " Al−Qasim said:
One may say to the widow: 'I hold all respect for you, and I
am interested in you; Allah will bring you much good, or
something similar 'Ata said: One should hint his intention,
and should not declare it openly. One may say: 'I have some
need. Have good tidings. Praise be to Allah; you are fit to
remarry.' She (the widow) may say in reply: I am listening to
what you say,' but she should not make a promise. Her guardian
should not make a promise (to somebody to get her married to
him) without her knowledge. But if, while still in the Iddat
period, she makes a promise to marry somebody, and he
ultimately marries her, they are not to be separated by
divorce (i.e., the marriage is valid).