Final answer:
The passage from Acts 1:4-8 implies speaking in tongues as the initial physical evidence of Holy Spirit baptism, notably described during the event of Pentecost.
Step-by-step explanation:
The Scripture passage that implies speaking in tongues as the initial physical evidence of Holy Spirit baptism can be found in Acts 1:4-8. This passage depicts the event of Pentecost, where the descent of the Holy Spirit upon the Apostles is described. The Apostles begin to speak in various languages, as the Spirit gives them utterance, which serves as evidence of the baptism in the Holy Spirit. Specifically, Acts 2 elucidates this phenomenon further, as it captures the Apostles speaking in different tongues and languages to the amazement of the onlookers who each hear the message in their own language. While other scripture passages, such as those in 1 Corinthians, discuss spiritual gifts and the resurrection, they do not directly associate speaking in tongues with the initial physical evidence of the baptism of the Holy Spirit.