B.G 2.14

मात्रास्पर्शास्तु कौन्तेय शीतोष्णसुखदुःखदाः। आगमापायिनोऽनित्यास्तांस्तितिक्षस्व भारत ॥ २-१४॥

O Kunti's Son, the contact of sense objects with senses causes pleasure and pain through the sensation of cold and heat. They come and go and are impermanent. Oh Arjuna, just endure them with firmness.

Gīta Bhāshya 2.14

It is the false attachment, 'abhimāna', that causes misery. In sleep, this attachment is absent and thus there is no misery.

तथाऽपि तद्दर्शनाभावादिना शोक इति चेत्- नेत्याह– मात्रास्पर्शा इति॥ मीयन्त इति मात्रा विषयाः। तेषां स्पर्शाः सम्बन्धाः। त एव शीतोष्णसुखदुःखदाः। देहे शीतोष्णादिसम्बन्धाद्धि शीतोष्णाद्यनुभव आत्मनः। ततश्च सुखदुःखे॥

Even then, if Arjuna is worried thinking he cannot see his relative, the 'matra-sparsha'(2-14) verse advocates that Arjuna should not worry. Senses perceive objects. One develops attachment when senses come in contact with the sense objects. From it arises the sensation of cold and heat, pleasure and pain. It is the body that comes in contact with cold and heat. It is 'atman' that experiences cold and heat, which causes pleasure and pain.

नह्यात्मनः स्वतो दुःखादिः सम्भवति। कुतः? आगमापायित्वात्। यद्यात्मनः स्वतः स्युः सुप्तावपि स्युः। अतो यतो मात्रास्पर्शा जाग्रदादावेव ते सन्ति नान्यदेति तदन्वयव्यतिरेकित्वात् तन्निमित्ता एव नात्मनः स्वतः॥

Atman does not on its own become miserable. Why? Because sensations are transitory, and they come and go. If the atman is itself the cause, then even in sleep one should experience pleasure and pain. But only in the awakened state, because of the contact of senses with the sense objects, one experiences pleasure and pain respectively, not otherwise.Thus, atman is not the root cause, but only instrumental.

आत्मनश्च तैर्विषयविषयिभावसम्बन्धादन्यः सम्बन्धो नास्ति। न चागमापायित्वेऽपि प्रवाहरूपेणापि नित्यत्वमस्ति। सुप्तिप्रलयादावभावादित्याह– अनित्या इति॥

The relationship of 'atman' is only that of topic and the sentiment attached towards that topic, no other. It is transient (agamapayi) like a stream, and not permanent. It is impermanent (anitya) because senses do not operate in deep sleep.

अतश्चात्मनो देहाद्यात्मभ्रम एव सुखदुःखकारणम्। अतस्तद्विमुक्तस्य बन्धुमरणादिदुःखं न सम्भवति। अतोऽभिमानं परित्यज्य तान् शीतोष्णादीन् तितिक्षस्व ॥ १४ ॥

Therefore, it is only the false attachment towards the body that causes pleasure and pain. One who has freed himself from such attachment does not experience misery because of the death of relatives. Therefore, one should leave attachment to oneself (abhimanam) and endure with firmness the heat and cold.