SB 4.6.41

tathāpare siddha-gaṇā maharṣibhir
 ye vai samantād anu nīlalohitam
namaskṛtaḥ prāha śaśāṅka-śekharaṁ
 kṛta-praṇāmaṁ prahasann ivātmabhūḥ
tathā — so; apare — the others; siddha-gaṇāḥ — the Siddhas; mahā-ṛṣibhiḥ — along with the great sages; ye — who; vai — indeed; samantāt — from all sides; anu — after; nīlalohitam — Lord Śiva; namaskṛtaḥ — making obeisances; prāha — said; śaśāṅka-śekharam — to Lord Śiva; kṛta-praṇāmam — having made obeisances; prahasan — smiling; iva — as; ātmabhūḥ — Lord Brahmā.
All the sages who were sitting with Lord Śiva, such as Nārada and others, also offered their respectful obeisances to Lord Brahmā. After being so worshiped, Lord Brahmā, smiling, began to speak to Lord Śiva.

Lord Brahmā was smiling because he knew that Lord Śiva is not only easily satisfied but easily irritated as well. He was afraid that Lord Śiva might be in an angry mood because he had lost his wife and had been insulted by Dakṣa. In order to conceal this fear, he smiled and addressed Lord Śiva as follows.