Ibn Majah

Hadith Commentary:
(1)
It is stated in the hadith that the responsibility of presenting witnesses lies upon the claimant (mudda‘i). If he is unable to present witnesses, then the decision will be made by having the defendant (mudda‘a ‘alayh) take an oath.
From this hadith, it is understood that in every situation, it is obligatory for the defendant to take an oath, provided that the claimant does not have witnesses—regardless of whether there is familiarity or a relationship between the claimant and the defendant or not.

(2)
Imam Malik rahimahullah says:
An oath will be taken from the defendant only when there has been an exchange of dealings and other transactions between the two; otherwise, every person would keep forcing any respectable individual to take an oath, even if it requires making a false claim against him.
Imam Bukhari rahimahullah’s position is that in both civil and criminal cases, an oath will be taken from the defendant, because there is no distinction regarding this in the ahadith; they should be maintained in their generality.
Our inclination is also towards this view.
And Allah knows best.

Hadith Commentary: Benefits and Issues:
This hadith establishes that if the claimant presents one witness for his claim and, in place of a second witness, takes an oath, then the judgment will be given in his favor.
The Imams of Hijaz (Malik, Shafi’i, Ahmad) hold this view.
This is also the opinion of the Rightly Guided Caliphs and the majority, and the hadith is an independent proof. The Qur’an, regarding any issue about which it is silent, can be established through solitary reports (akhbar ahad), because such reports do not abrogate (naskh) but rather clarify (bayan), as Allamah Taqi himself has accepted and has also transmitted from Allamah ‘Ayni.
(Takmila, vol. 2, pp. 564-565)
Therefore, to consider this hadith as opposing or contradicting the Qur’an is merely the result of blind following (taqlid), because the Qur’an, in specifying the standard of testimony, mentions the testimony of two men or one man and two women, and is silent regarding the third scenario—one witness and an oath—which the hadith has clarified.
Similarly, to declare the five hadiths indicating witness and oath as weak is obstinacy, for this reason Allamah Taqi has acknowledged that “la majala li inkar thubutiha”—there is no room to deny their authenticity.
(Takmila, vol. 2, p. 564)
And these are not solitary reports (akhbar ahad), but according to Allamah Taqi, in the terminology of the Hanafis, they are mashhoor (well-known), p. 563.
And according to the principles of the Hanafis, specification (takhsis) of a Qur’anic text can be made by a well-known report (khabar mashhoor), whereas according to the majority of the Imams, specification is clarification (bayan), not abrogation (naskh), and specification by a solitary report (khabar wahid) is permissible.
Al-Wajiz, p. 319 (Al-Wajiz fi Usul al-Fiqh), Dr. Abdul Karim Zaidan.