Sahih al-Bukhari — Wedlock, Marriage (Nikaah) — Hadith No: 5124
Translation
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)