Glad tidings of martyrdom to Hadhrat Uthman
There is a Hadith in Sahih Bukhari:
Translation of Hadith: It has been narrated on the authority of Hadhrat Anas Bin Malik (May Allah be well pleased with him), he said that the Holy Prophet (Sallallahu alaihi wa sallam) graced the mountain of Uhud with His presence along with Hadhrat Abu Bakr Siddiq, Hadhrat Umar Farooq and Hadhrat Uthman (May Allah be well pleased with them). The mountain of Uhud started swaying out of happiness. The Holy Prophet (Sallallahu alaihi wa sallam) tapped it with His foot and said: O mountain! Be steady! The Prophet is on you and 1 Siddiq and 2 Shaheed (martyrs)
(Sahih Bukhari, Hadith No: 3686)
Imam Jalaluddin Suyuti (May Allah shower His mercy on him) has narrated a Hadith on the authority of Ibn Asaker:
Translation of Hadith: It has been narrated on the authority of Hadhrat Zaid Bin Thabit (May Allah be well pleased with him), he said that I heard the Holy Prophet (Sallallahu alaihi wa sallam) say: Uthman passed by Me. At that time, an angel was present before Me. He said: Hadhrat Uthman is a Shaheed . His own people will martyr him. All us angels, are shy of Uthman.
(Tarikh Ul Khulafa, Vol. 1, Pg. No. 62)
Glad tidings of Jannah
Hadhrat Uthman is from among the Ashra Mubasshira i.e. those 10 people who have been glad tidings of Jannah in this world and Hadhrat Uthman bought Jannah from the Holy Prophet (Sallallahu alaihi wa sallam) 2 times, as given in Mustadrak Alas Sahihain :
It has been narrated on the authority of Hadhrat Abu Hurairah (May Allah be well pleased with him), he said that Hadhrat Uthman (May Allah be well pleased with him) bought Jannah definitely bought Jannah from the Holy Prophet (Sallallahu alaihi wa sallam) 2 times: At the time when “Birr Mau’oona” was dug and on providing for the Jaish ‘Usrat . Imam Hakim (May Allah shower His mercy on him) said that this Hadith has a rigorously authenticated ( Sahih ) chain of narration.
(Mustadrak Alas Sahihain, Hadith No: 44564)
His progeny
Hadhrat Uthman got 1 son from Hadhrat Ruqaiyyah (May Allah be well pleased with her), whose name is Hadhrat Abdullah (May Allah be well pleased with him).
His caliphate
Hadhrat Uthman (May Allah be well pleased with him) was seated on the caliphate the 3rd day after the burial of Hadhrat Umar Al Farooq (May Allah be well pleased with him), as per “Tarikh Ul Khulafa” and his caliphate was for 12 years.
His martyrdom
He was martyred in Dhul Hijjah, 35 Hijri, Friday after Salaat Ul ‘Asr. His blessed grave is in Jannatul Baqee.