Fiqh-us-Sunnah Volume 5, Hajj and ‘Umrah, Fiqh 5.035.
Section : Putting on Ihram Without Specifying Its Kind.
If a person puts on ihram with the intention of performing whatever Allah has prescribed for him without specifying any of the above three kinds due to lack of knowledge. his ihram would be quite lawful and valid.
The scholars said: “If such a person utters talbiyah like others with the intention of performing the rituals (of Hajj), but says nothing in words, nor makes an intention in his heart, nor specifies whether it is tamattu’, ifrad, or qiran Hajj that he intends, his pilgrimage would still be valid, and he will be reckoned to have made one of the three kinds of Hajj.