What action did Abu Bakr refrain from taking out of respect for the secret of the Prophet Muhammad (saw)?
 Narrated `Abdullah bin `Umar:                     `Umar bin Al-Khattab said, "When (my daughter) Hafsa bint `Umar lost her husband Khunais bin Hudhaifa As-Sahrni who was one of the companions of Allah's Apostle and had fought in the battle of Badr and had died in Medina, I met `Uthman bin `Affan and suggested that he should marry Hafsa saying, "If you wish, I will marry Hafsa bint `Umar to you,' on that, he said, 'I will think it over.' I waited for a few days and then he said to me. 'I am of the opinion that I shall not marry at present.' Then I met Abu Bakr and said, 'if you wish, I will marry you, Hafsa bint `Umar.' He kept quiet and did not give me any reply and I became more angry with him than I was with `Uthman . Some days later, Allah's Apostle demanded her hand in marriage and I married her to him. Later on Abu Bakr met me and said, "Perhaps you were angry with me when you offered me Hafsa for marriage and I gave no reply to you?' I said, 'Yes.' Abu Bakr said, 'Nothing prevented me from accepting your offer except that I learnt that Allah's Apostle had referred to the issue of Hafsa and I did not want to disclose the secret of Allah's Apostle , but had he (i.e. the Prophet) given her up I would surely have accepted her."