Should the verbalization of the intention for 'Umrah or Hajj be with the heart or with the tongue, and is it better to say, "I intend 'Umrah" or "Here I am for 'Umrah"?

When pronouncing the Talbiyah, it is recommended to mention what one intends to perform for the Ihram, whether it is Hajj, Umrah, or both. For example, one may say: "Labbayka Umrah" (Here I am for Umrah), or "Labbayka Hajj" (Here I am for Hajj), or "Labbayka Umrah wa Hajj" (Here I am for Umrah and Hajj). This act is recommended, not obligatory, as the intention resides in the heart. It is not sunnah to verbally declare "I intend Umrah" or "I intend Hajj," because this was not transmitted from the Prophet, peace and blessings be upon him.