Friction is a force that opposes the relative motion between two surfaces in contact. However, in the case you mentioned, where there is no contact with the surface, it's not friction that stops the oscillatory motion.
Oscillatory motion refers to a repeated back-and-forth movement around an equilibrium position. If there is no contact with a surface, there might be another force or mechanism at play that causes the oscillatory motion to stop. Here are a few possibilities:
Damping: Oscillatory systems often experience damping, which is the dissipation of energy over time. Damping can arise from various sources, such as air resistance, internal friction within the system, or the presence of a damping medium like a fluid. As the energy of the oscillating system is gradually dissipated, the motion eventually comes to a halt.
Energy loss: Oscillatory systems can lose energy through various mechanisms, such as radiation of energy in the form of sound or heat. Over time, the energy loss can cause the oscillations to gradually diminish until they stop completely.
External forces: There may be external forces acting on the system that counteract the oscillatory motion. These forces could arise from sources such as gravity, electromagnetic fields, or other interacting objects in the vicinity. Depending on the nature and strength of these forces, they can bring the oscillations to a halt.
It's essential to note that friction itself requires contact between surfaces to exert its influence. In the absence of contact, other forces or factors are typically responsible for stopping an oscillatory motion.