At the start of chapter two, Arjuna has dropped his bow. Sañjaya describes him at 2.1: overcome with pity, sorrow-stricken, his eyes wet with tears. Search the whole Gītā and it is the only verse where anyone cries.
Nine verses later, at 2.10, Kṛṣṇa answers him. Sañjaya says he spoke as if smiling. That is the only smile in the Gītā, the only place the word prahasan appears.
The teaching that follows runs to the end of chapter eighteen. It begins here, with a man in tears and a friend who smiles at him before saying a single word of it.
The smile comes first. The words come after.
The verses
BHAGAVAD GĪTĀ · 2.1सञ्जय उवाच
तं तथा कृपयाऽविष्टमश्रुपूर्णाकुलेक्षणम्।
विषीदन्तमिदं वाक्यमुवाच मधुसूदनः।।
sañjaya uvāca
taṁ tathā kṛpayāviṣṭamaśru pūrṇākulekṣaṇam
viṣīdantamidaṁ vākyam uvāca madhusūdanaḥ
Sanjaya said: To him, who was overcome with pity, whose eyes were wet with tears, who was sorrow-stricken and bore a bewildered look, Sri Krishna spoke as follows:
BHAGAVAD GĪTĀ · 2.10तमुवाच हृषीकेशः प्रहसन्निव भारत।
सेनयोरुभयोर्मध्ये विषीदन्तमिदं वचः।।
tam-uvāca hṛṣīkeśaḥ prahasanniva bhārata
senayorubhayor-madhye viṣīdantam-idaṁ vacaḥ
O King, to him who was thus sorrowing between the two armies, Sri Krishna spoke the following words, as if smiling (by way of ridicule).
Going deeper
Chapter 1 ends with 1.47: Sañjaya reports that Arjuna threw down his bow and arrows and sat on the chariot seat, his heart overwhelmed with grief. 2.1 picks up from there. Arjuna is full of pity, his eyes are wet with tears, he is sorrow-stricken and bewildered, and Kṛṣṇa speaks to him. 2.2 is Kṛṣṇa's first reply, asking where this despondency comes from at a time of crisis. After Arjuna says in 2.9 that he will not fight and falls silent, 2.10 shows Kṛṣṇa answering, as if smiling, the one who is sorrowing between the two armies. The real teaching opens in 2.11. The two verses give a picture of the start of a lesson: one person weeping, and the other meeting that with a smile before any words of instruction. See chapter 2 and what the Gītā says about grief.