Without letting me say a word, he pulled me into the house.
Tips
history
Found in the Yuan play 《生金阁》 act 3: 怎么不由分说,便将我飞拳走踢只是打 - 'why, without giving me a chance to explain, do you just rain kicks and punches?' Colloquial Yuan-drama vocabulary that fossilized into standard written use.
grammar
Functions adverbially - usually followed directly by a verb phrase (不由分说 + VP). Common with 把-constructions: 不由分说把...+ verb.