Assalamualikum Mufti Sahib,
If a person is perfoming salat in the four line (saf) can a person walk a cross you from the first saf.
Wa Alaikum As Salaam,
The best is that the person places a sutra before crossing. However, if this is not done then it will be allowed for him to pass from the first saff if you are in the 4th saff.
And Allah knows best,
Mufti Waseem Khan