Musannaf Ibn Abi Shaybah

Hazrat Tawus says that it is not necessary for you to mention the name of Hajj or Umrah; your intention alone will suffice for you.

Ibrahim says that when you intend to enter into Ihram, do not mention the name of anything; indeed, only that will be obligatory upon you which you intended, whether Hajj or Umrah.

Hazrat Ibn Umar (may Allah be pleased with both of them) states that it is sufficient for you to intend Hajj or Umrah when you make the intention to wear the Ihram.

Hazrat Saeed says that I performed Hajj with some companions of Hazrat Abdullah; when they entered into Ihram, they did not mention any name, etc., and this remained their practice until they became old (i.e., this was their habit in old age as well).

Hazrat Ata says that intention will suffice for it.

Hasan was asked that a person made Hajj and Umrah obligatory upon himself but did not mention the names of either of them? He replied that whichever he intended and resolved upon, that will be counted, and he used to instruct that the name should be mentioned.

Hazrat Saeed bin Jubair says that intention alone is sufficient for it.

Ibrahim says that intention alone will suffice for it.