It occurs occasionally that Zaid's neighbour leaves his Wi-Fi open.

Answer

Although the gigabytes are unlimited and use by others will not monetarily prejudice the one paying for the unlimited bytes, experts say that it would slow down the transmission process. When others use the internet, the speed is affected. Zaid therefore has to first obtain consent from his neighbour. However, if it is known that the Wi-Fi has been left open for use by others, then it will be permissible to use without prior permission Presently the only factor of which we are aware which makes incumbent permission from the payer, is interference with the speed. If any expert is aware of any other factors which could be added to this one element, we shall appreciate to be apprized thereof.