Dear sister, first of all tell ur friend to get out of this mindset that Allah has weight, height, volume etc. Allah is not a person or thing that we can imagine or picturize of. Sometime people gets confused that Allah is a person like heavenly father of Christianity but Allah could not be compared to anything that we can imagine in this world. So first u need to tell them what Allah is and try to change their concept of Allah they have in their mind. Quote the verse" say, Allah one and only, he is absolute and eternal, he does not beget, nor he is begotten, and there is nothing like onto him" so the last part of the verse"..there nothing like onto him" says that nothing could be imagined or compared with Allah. The Quran gives 99 attributes of Allah, like most gracious, most merciful, most knowledgeable etc. but none of the attributes are like Father, Son, Holy Ghost who might have height, mass, volume, weight, image or look etc. So ur friends have wrong concept of Allah maybe coz may be they think of christian concept of god.