Witnesses to zina when they are fewer than four

Qasamah bin Zuhayr (may Allah have mercy on him) says: When the affair of Sayyiduna Abu Bakrah and Sayyiduna al-Mughirah (may Allah be pleased with them both) took place, he then mentioned the long hadith, in which it is also stated that witnesses were called, and Sayyiduna Abu Bakrah, Shibl bin Ma'bad and Abu Abdullah Nafi' (may Allah be pleased with them) gave testimony. When these three had testified, it weighed heavily on Sayyiduna Umar (may Allah be pleased with him). When Ziyad stood up to give testimony, he said: 'In sha' Allah' (if Allah wills), I will testify with the truth. As for adultery, I did not see that, but I did see them in a very bad state. Sayyiduna Umar (may Allah be pleased with him) said 'Allahu Akbar' (Allah is the Greatest) and ordered that the hadd punishment for false accusation (qadhf) be applied to them.
Even after the hadd had been applied, Sayyiduna Abu Bakrah (may Allah be pleased with him) kept saying: 'Wallahi' (by Allah), he committed adultery. So Sayyiduna Umar (may Allah be pleased with him) again intended to apply the hadd to him, but Sayyiduna Ali (may Allah be pleased with him) said: If you apply the hadd to him a second time, you will have to stone al-Mughirah. So Sayyiduna Umar (may Allah be pleased with him) held back.

Qatadah narrates that Sayyiduna Abu Bakrah, Nafi' bin al-Harith and Shibl bin Ma'bad (may Allah be pleased with them) testified against Sayyiduna al-Mughirah bin Shu'bah (may Allah be pleased with him) that they had seen him inserting it and withdrawing it. Ziyad was the fourth witness. These three gave their testimony (and one of them said:) I even saw its marks on her thigh. When Sayyiduna Umar (may Allah be pleased with him) saw Ziyad, he said: "This lad is a good one; he will say nothing but the truth, and he will not hide anything from me either." Ziyad said: "I did not see it in the state these men are describing, but I saw them in a suspicious state, and their breathing was heavy." So Sayyiduna Umar (may Allah be pleased with him) applied the hadd punishment for false accusation (qadhf) to those three and let Ziyad go.
This narration has also come with a connected chain in these words: the four of them (Abu Bakrah, Ziyad, Nafi' and Shibl) were in an upper room, and Sayyiduna al-Mughirah (may Allah be pleased with him) was in the lower part of the house. A wind came, which opened the door and lifted the curtain, and they saw Sayyiduna al-Mughirah (may Allah be pleased with him) between her legs. They said to one another: We have been put to the test. Then he mentioned the whole story. Sayyiduna Abu Bakrah, Nafi' and Shibl testified, and Ziyad said: I do not know whether he had intercourse with her or not. So Sayyiduna Umar (may Allah be pleased with him) flogged all of them except Ziyad. Sayyiduna Abu Bakrah (may Allah be pleased with him) said: Have you not already flogged me? He said: Indeed. He said: Then I testify by Allah that he did it. Sayyiduna Umar wanted to flog him again, but Sayyiduna Ali said: If the testimony of Abu Bakrah counts as the testimony of two men, then stone your companion (al-Mughirah); otherwise, you have already flogged him, meaning that he is not flogged a second time for repeating the accusation.

It is narrated from Abd al-Rahman (may Allah be pleased with him); this hadith has already passed earlier under number 17043.