يلزمه الحج بأفعال معلومة لوجود العرف
A vow expressed as Hajj or going to God's House is understood through the customary set of Hajj rites.
The phrase 'go to the House' can literally describe physical movement, but within devotional vows it points to a recognized ritual practice. Merely reaching a building does not necessarily exhaust that devotional expression.
The methodological point is that an established religious term can designate a complete recognized act rather than one isolated physical action.
The full legal enforceability of a vow depends on further conditions. Here the issue is specifically how established usage determines the intended scope of the wording.