This paper presents a solution to the source exploration problem for multiple robots under the formation consensus within a prescribed time. To this end, we design a switching control strategy to drive robots to complete collaborative tasks, which is divided into two stages. The first stage builds a formation consensus algorithm by coupling a time-varying scaling function to reach the desired location in the prescribed time for robots. The second stage puts forward a control scheme based on an adaptive strategy and a predefined-time velocity estimator to complete source exploration under no velocity measurements, where the adaptive strategy is designed combined with the projection operator to estimate the unknown parameters of the scalar field. Eventually, a simulation test is performed to verify the effectiveness of the proposed scheme.