<p>4:31 <em>And when they had prayed, the place was shaken wherein they were gathered together</em>- Presumably by an earthquake. But they were unharmed. The same scenario is found when Paul was in trouble with the authorities in Philippi. In response to his midnight prayers, the place was shaken by an earthquake (Acts 16:26 s.w.). Paul was hereby confirmed in seeking to emulate Peter's ministry; for now something beyond his conscious imitation occurred, i.e. an earthquake after prayer, which reinforced his understanding of his ministry as being based upon Peter's. His willing taking humble Peter for his example was an essay in humility. See on 4:29 <em>To speak Your word with all boldness</em>.</p><p><em>And they were all filled with the Holy Spirit</em>- The situation is intended to recall that in Acts 2. Here, they are gathered together in one place, presumably that same upper room. They prayed, and were filled with Holy Spirit. I suggested on 4:29 that this was more in the form of internal strengthening. But I think it was also in chapter 2, but there was visible manifestation for emphasis. In this case, the more physical manifestation of the Spirit was in the earthquake. We also observe that being filled with the Holy Spirit was an experience which had to be repeated; they had been filled with it in chapter 2, and were now filled with it again. It gave specific strength at specific times.</p><p><em>And they spoke the word of God with boldness</em>- See on 4:29 <em>To speak Your word with all boldness</em>. When Paul is recorded as speaking the word with boldness (Acts 13:46) and praying that he would speak the world boldly as he ought to (Eph. 6:20), surely he was allowing himself to be inspired by Peter's example and consciously seeking to follow it. This huge respect for Peter by Paul is a powerful essay in humility. For they were from very differing social, cultural and educational backgrounds; in secular terms, Paul the Roman citizen was born far higher than Peter the Galilean fisherman.</p>