This is a well-known point of scholarly disagreement among the four schools. The Shafi'i and Hanbali schools hold that Umrah is wajib (wajib) once in a lifetime for every Muslim who has the physical and financial ability — similar to Haji but without the specific time restriction. The Hanafi and Maliki schools consider Umrah to be a confirmed Sunnah (Sunnah mu'akkadah) that is highly sunnah but not wajib.
Sheikh Ibn Baz held the position that Umrah is wajib once in a lifetime, following the Hanbali and Shafi'i position. He cited the hadith where a bedouin asked Nabi about Umrah: 'Is Umrah wajib?' and Nabi said: 'No, but if you perform Umrah, it is better for you.' However, he noted that other narrations and Al-Al-Quran's command 'And complete the Haji and Umrah for Allah' support the obligation. He reconciled the evidence by concluding that Umrah is wajib.
Sheikh Al-Fawzan similarly held Umrah to be wajib, stating that the conjunction of Umrah with Haji in Al-Al-Quranic verse — 'And complete the Haji and Umrah for Allah' (Al-Baqarah, 2:196) — indicates that they share the same ruling of obligation. He acknowledged the opposing view but considered the evidence for obligation to be stronger. Those who hold Umrah to be Sunnah note that Nabi's statement 'No' in response to 'Is it wajib?' is explicit, while those who hold it wajib interpret that hadith differently.