B.G 2.14

मात्रास्पर्शास्तु कौन्तेय शीतोष्णसुखदुःखदाः। आगमापायिनोऽनित्यास्तांस्तितिक्षस्व भारत ॥ २-१४॥

O son of Kunti, the contacts of sense objects with senses cause pleasure and pain through the sensation of cold and heat, and are impermanent; endure them, O descendant of Bharata.

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 if there is sorrow due to the absence of that sight (thinking he cannot see his relative), it is said that the contacts of the senses are the sources of cold, heat, pleasure, and pain. The experiences of cold, heat, etc., in the body are indeed due to their connection. Consequently, there are 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॥

Suffering and similar experiences do not originate from the being by themselves. Why is this so? Because they are transient. If they were inherent in the being, they would persist even during sleep. Since sensory experiences occur only during waking and similar states and not otherwise, it is due to their association and dissociation with external factors, not by the essense of the being itself.

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

There is no other relationship to the being with them apart from the subject-object relationship. It is transient (agamapayi) like a stream, and not permanent. It is said to be impermanent (anitya) because of its absence at the beginning of creation (during deep slumber) and dissolution.

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

Therefore, the illusion of identifying the self with the body is the cause of happiness and sorrow. For one who is liberated, sorrow from relationships and death does not occur. Thus, abandoning pride, endure conditions like cold and heat.