Tasmātiha, bhikkhave, setughāto gīte, setughāto nacce, alaṁ vo dhammappamoditānaṁ sataṁ sitaṁ sitamattāyā”ti.  So break off singing and dancing; and when you’re appropriately pleased, it’s enough to simply smile.” 

pekkhitena sitena ca;  with a glance and a smile. 
sitena ca → mhitena ca (sya-all, km, pts1ed) 

Idha, bhikkhave, bhikkhuṁ araññagataṁ vā rukkhamūlagataṁ vā suññāgāragataṁ vā mātugāmo upasaṅkamitvā ūhasati ullapati ujjagghati uppaṇḍeti.  It’s when a mendicant who has gone to a wilderness, or to the root of a tree, or to an empty hut is approached by a female. She smiles, chats, laughs, and teases him. 
ūhasati → ohasati (sya-all, km); uhasati (mr) | ujjagghati → ujjhagghati (bj); ujjhaggeti (pts1ed) 

disvāna maggā okkamma yena taṁ sālavanaṁ tenupasaṅkami; upasaṅkamitvā taṁ sālavanaṁ ajjhogāhetvā aññatarasmiṁ padese sitaṁ pātvākāsi.  He left the road, went to the sal grove, and plunged deep into it. And at a certain spot he smiled. 
disvāna → disvā (bj, pts1ed) | okkamma → ukkamma (katthaci) 
“ko nu kho hetu ko paccayo bhagavato sitassa pātukammāya? 
“What is the cause, what is the reason why the Buddha smiled? 
Na akāraṇena tathāgatā sitaṁ pātukarontī”ti. 
Realized Ones do not smile for no reason.” 
“ko nu kho, bhante, hetu ko paccayo bhagavato sitassa pātukammāya? 
“What is the cause, what is the reason why the Buddha smiled? 
Na akāraṇena tathāgatā sitaṁ pātukarontī”ti. 
Realized Ones do not smile for no reason.” 

Mahesī vā bhikkhuṁ disvā sitaṁ pātukaroti, bhikkhu vā mahesiṁ disvā sitaṁ pātukaroti.  When the queen sees the monk she smiles, or when the monk sees the queen he smiles. 

Samaṇo khalu, bho, gotamo ehisvāgatavādī sakhilo sammodako abbhākuṭiko uttānamukho pubbabhāsī …pe…  He is welcoming, congenial, polite, smiling, open, the first to speak. … 

Samaṇo khalu, bho, gotamo ehisvāgatavādī sakhilo sammodako abbhākuṭiko uttānamukho pubbabhāsī …pe…  He is welcoming, congenial, polite, smiling, open, the first to speak. … 

Atha kho bhagavā maggā okkamma aññatarasmiṁ padese sitaṁ pātvākāsi.  Then the Buddha left the road, and at a certain spot he smiled. 
“ko nu kho hetu, ko paccayo bhagavato sitassa pātukammāya? 
“What is the cause, what is the reason why the Buddha smiled? 
Na akāraṇena tathāgatā sitaṁ pātukarontī”ti. 
Realized Ones do not smile for no reason.” 
Na akāraṇena → na akāraṇe (bj) 
“ko nu kho, bhante, hetu, ko paccayo bhagavato sitassa pātukammāya? 
“What is the cause, what is the reason why the Buddha smiled? 
Na akāraṇena tathāgatā sitaṁ pātukarontī”ti. 
Realized Ones do not smile for no reason.” 

Atha kho bhagavā aññatarasmiṁ padese sitaṁ pātvākāsi.  Then the Buddha smiled at a certain spot. 
“ko nu kho hetu, ko paccayo bhagavato sitassa pātukammāya? 
“What is the cause, what is the reason why the Buddha smiled? 
Na akāraṇena tathāgatā sitaṁ pātukarontī”ti. 
Realized Ones do not smile for no reason.” 
“ko nu kho, bhante, hetu, ko paccayo bhagavato sitassa pātukammāya? 
“What is the cause, what is the reason why the Buddha smiled? 
Na akāraṇena tathāgatā sitaṁ pātukarontī”ti. 
Realized Ones do not smile for no reason.” 

Idha panāhaṁ, bhante, bhikkhū passāmi haṭṭhapahaṭṭhe udaggudagge abhiratarūpe pīṇindriye appossukke pannalome paradattavutte migabhūtena cetasā viharante.  But here I see mendicants always smiling and joyful, obviously happy, with cheerful faces, living relaxed, unruffled, surviving on charity, their hearts free as a wild deer. 
pīṇindriye → pīṇitindriyā (bj); pīṇitindriye (pts1ed) 
tathā hi ime āyasmanto haṭṭhapahaṭṭhā udaggudaggā abhiratarūpā pīṇindriyā appossukkā pannalomā paradattavuttā migabhūtena cetasā viharantī’ti. 
That’s why these venerables are always smiling and joyful, obviously happy, with cheerful faces, living relaxed, unruffled, surviving on charity, their hearts free as a wild deer.’ 

Atha kho bhagavā sitaṁ pātvākāsi.  At that, the Buddha smiled. 

Atha kho anāthapiṇḍiko gahapati, nāmena maṁ bhagavā ālapatīti, haṭṭho udaggo tattheva bhagavato pādesu sirasā nipatitvā bhagavantaṁ etadavoca:  Then Anāthapiṇḍika thought, “The Buddha calls me by name!” Smiling and elated, he bowed with his head at the Buddha’s feet and said to him, 

Atha kho āyasmā mahāmoggallāno gijjhakūṭā pabbatā orohanto aññatarasmiṁ padese sitaṁ pātvākāsi.  As Mahāmoggallāna was descending from Vulture’s Peak Mountain he smiled at a certain spot. 
“ko nu kho, āvuso moggallāna, hetu ko paccayo sitassa pātukammāyā”ti? 
“What is the cause, Reverend Moggallāna, what is the reason you smiled?” 
“idhāyasmā mahāmoggallāno gijjhakūṭā pabbatā orohanto aññatarasmiṁ padese sitaṁ pātvākāsi. 
“Just now, as Mahāmoggallāna was descending from Vulture’s Peak Mountain he smiled at a certain spot. 
Ko nu kho, āvuso moggallāna, hetu ko paccayo sitassa pātukammāyā”ti? 
What is the cause, Reverend Moggallāna, what is the reason you smiled?”