During his lifetime the Holy Prophet pronounced on various matters. When any one met with a problem he went to the Holy Prophet for his verdict. Such decisions remained know to the persons concerned and were not publicised. As such the decisions of the Holy Prophet remained wide spread. The traditions were not compiled in any compendium and as such the sources remained scattered. In view of the diffusion of resources there grew the risk that some traditions reported might be spurious or coloured with the views or prejudices of the narrator.
Umar was the first to realise the necessity of the proper sifting of the traditions. Umar accordingly founded the science of Hadith. The practice with Umar was that if any new problem cropped up, Umar announced in the public assembly the point at issue, and inquired if any of them remembered any tradition of the Holy Prophet on the subject. Those who narrated any tradition were required to produce some witnesses in support of the tradition. If such statement was duly corroborated and was in accordance with the spirit of the Holy Quran as well as common sense it was adopted and applied to the facts of the case in hand. In this way a rich corpus of Hadith was built up. These were recorded and copies were supplied to all provinces for guidance. Umar deputed experts in Hadith to various provinces to educate the provincial officers in Hadith.
Umar classified the traditions in two broad categories. One category of traditions pertained to religious, moral and social affairs pertaining to the community at large. These matters emanated from the prophetic mission of the Holy Prophet. The other traditions revolved round the person of the Holy Prophet and pertained to his words and deeds as a human being. Umar distinguished between these two categories and took care to ensure that these two categories did not get mixed up. All matters falling in the first category were binding and had the status of law. The matters falling in the second category remained as ideals to be followed, but these did not have the status of law. Umar took particular care to disseminate all traditions falling in the second category. The traditions in the second category were sparingly reported or publicised.
Umar was alive to the danger that whatever was ascribed to the Holy Prophet, right or wrong would obtain currency and venerable acceptance. Umar evolved principles on the basis of which the traditions were to be accepted. The basic principles were:
(1) The report should be literally faithful;
(2) Every Hadith narrated should carry with it the name of the narrator and the chain of narrators;
(3) The narrators must be men of proven faith and integrity;
(4) In judging the veracity of a report the occasion and circumstances involved should be taken into consideration;
(5) The report should not be repugnant to the Holy Quran;
(6) The report should be rational.
There was some dispute about the number of takbirs to be said in funeral prayers. Sufficient evidence was adduced to the effect that the Holy Prophet offered four takbirs. It was accordingly laid down by Umar that in funeral prayers four takbirs should be said. The matters regarding bath for sexual impurity, Jizyah to be levied on Magians and other allied matters were decided in the light of authentic traditions of the Holy Prophet.
It is related that Abu Musa Ash'ari the Governor of Basra once came to see Umar and by way of permission said "Assalamulaikam". Umar was busy and did not pay attention to Abu Musa. Abu Musa repeated the greetings thrice and then went away. Umar had him recalled and enquired why he had gone away. Abu Musa said that he had heard the Holy Prophet say, "Ask permission thrice, and if you do not get permission go away". Umar asked for corroborative evidence in support of the tradition. Abu Musa produced the evidence and the tradition was accepted as a guide.
In the time of Umar a question arose whether a , woman who had been divorced but the divorce had not become I effective could remain in the house of her husband. A lady Fatima bint Qais stated before Umar that she had it on the authority of the Holy Prophet that such woman could no longer lodge with her husband. The Holy Quran clearly provided that such woman could lodge with her husband till the divorce became effective. Umar accordingly ruled: "We cannot abandon the Book of Allah on the word of a woman, for we do not know whether she remembers the tradition correctly or has forgotten it."
Lest the people should make mistakes in reporting Hadith direct from the Holy Prophet, Umar forbade the Companions to report direct from the Holy Prophet. Umar also enjoined that Hadith should not be mixed with the Quran. Lest there might be mistake in reporting. Umar enjoined, "Report sparingly from the Holy Prophet". When Umar was asked to quote traditions he would usually say "Had I not feared that I might make a mistake in reporting Hadith I would have quoted one." Umar emphasised that extra care should be taken to ensure that there was no mistake in reporting. The checks and restraints imposed by Umar on the reporting of traditions and the high standard of accuracy required by him paid dividends and all the traditions that were accepted and publicised were free from flaw.