In which Surah was the Verse of the Sword revealed and what is its number? And is it valid to pray Dhuhr and Asr two Rak'ahs while traveling?

The verse of the sword in Surat at-Tawbah is the fifth verse: ﴿And when the sacred months have passed, then kill the polytheists wherever you find them and capture them and besiege them and sit in ambush for them at every lookout. But if they repent and establish prayer and give zakah, then let them [go their] way. Indeed, Allah is Forgiving and Merciful.﴾

The traveler's shortening of prayer before passing the houses of the city is incorrect. As for the Asr prayer after its time has begun and after passing the houses of the city, it is correct.