Reference: Sharh ‘Umdatil-Fiqh – Tape 1, Question No.24
Question: Whoever prays alongside to the right of the imaam, while there is space [in the row] behind him – is there any problem with that?
Response: There is no harm in that, there is no harm in that. He [can] pray [alongside] to the right of the imaam – even if there is space in the rows [behind him].